PostgreSQL Errors

PostgreSQL error 22025 occurs when a backslash escape sequence in a string literal or bytea constant is not recognized. This happens when backslashes are not properly escaped or when escape syntax is used incorrectly.

PostgreSQL has stopped accepting write commands to prevent transaction ID wraparound from corrupting data. This emergency shutdown occurs when the database approaches the critical 2-billion-transaction threshold and autovacuum has failed to freeze old transaction IDs.

This error occurs when attempting to set a different transaction isolation level within a subtransaction (savepoint) or when the isolation level does not match between a parent transaction and its branch.

The PostgreSQL error "42P19: invalid_recursion" occurs when a recursive Common Table Expression (CTE) is improperly structured. This syntax error prevents recursive queries from executing and typically indicates missing or incorrect references to the CTE itself in the recursive term. Fixing it requires understanding PostgreSQL's rules for recursive query construction.

The PostgreSQL error "2202G: invalid_tablesample_repeat" occurs when using the TABLESAMPLE clause with an invalid REPEAT parameter value. This error indicates that the REPEAT parameter provided to the TABLESAMPLE clause is outside the valid range (0 to 2^31-1) or has an incorrect data type.

The PostgreSQL error "428C9: generated_always" occurs when attempting to insert or update a value in a GENERATED ALWAYS column, which violates the column's generation constraint. This error indicates that you're trying to manually modify a column that PostgreSQL automatically manages based on other column values.

PostgreSQL raises HV005 when a foreign-data wrapper tries to bind a local column that no longer exists on the remote object, which typically happens after the remote schema change or a mis-specified fdw_column_name mapping. Aligning the foreign table definition with the remote table (or dropping the dead column) restores the column metadata and lets the query run again.

The PostgreSQL error "20000: case_not_found" occurs in PL/pgSQL when a CASE statement executes without matching any WHEN condition and no ELSE clause is provided. This runtime error indicates that the CASE expression failed to find a matching branch, causing the function or procedure to abort.

This error occurs when PostgreSQL encounters an improperly formatted escape sequence in a bytea (binary data) value. The issue typically arises when using escape format with invalid octal values or incorrect backslash escaping.

This error occurs when the PostgreSQL server and client have incompatible TLS/SSL protocol versions. The server rejects the connection because the client's TLS version doesn't match the server's minimum or maximum allowed versions. Update your client software or adjust server SSL configuration to fix this.

PostgreSQL error 42803 occurs when you attempt to nest one aggregate function (like COUNT, SUM, AVG) directly inside another aggregate function. Use subqueries, CTEs, or window functions to break the nesting into multiple query levels.

PostgreSQL does not support nesting aggregate functions directly (such as AVG(MAX(column))). Use subqueries or Common Table Expressions (CTEs) to perform multi-level aggregations.

This error occurs when PostgreSQL receives a connection attempt but cannot find a matching rule in the pg_hba.conf configuration file. It typically happens when connecting from an IP address, hostname, or with a user/database combination that isn't explicitly allowed. Add the missing entry to pg_hba.conf and reload the database to fix it.

This error occurs when you attempt to INSERT or UPDATE data through a view with WITH CHECK OPTION, but the new row doesn't satisfy the view's WHERE condition. PostgreSQL prevents the operation to maintain view constraints.

This warning indicates your code uses a deprecated PostgreSQL feature. Update to the recommended modern alternative to ensure compatibility with future versions.

The PostgreSQL "function does not exist" error (SQLSTATE 42883) occurs when a function call cannot be matched to any defined function with the same name and argument types. This is commonly caused by mismatched data types, missing extensions, incorrect schema qualification, or typos in the function name. PostgreSQL requires exact matches on both function name and parameter types.

The 42P17 error occurs when PostgreSQL detects an invalid database object definition, most commonly when creating generated columns with non-immutable expressions or defining objects with conflicting constraints.

PostgreSQL error 23000 (Integrity Constraint Violation) occurs when an INSERT, UPDATE, or DELETE operation breaks a primary key, foreign key, unique, or check constraint. This is a parent error class that includes more specific violations like 23505 (unique violation) and 23503 (foreign key violation). Fixing requires identifying the specific constraint, validating referenced data, or using ON CONFLICT clauses to handle conflicts gracefully.

This error occurs when you reference a schema that does not exist in the current PostgreSQL database. It commonly happens when executing queries, creating objects, or setting search paths that reference non-existent schemas. The solution involves verifying the schema exists or creating it before use.

This Foreign Data Wrapper (FDW) error occurs when an option value provided to CREATE FOREIGN TABLE or ALTER FOREIGN TABLE is invalid or incompatible with the FDW implementation.

This error occurs when trying to use a WITH HOLD cursor in a transaction with a different isolation level than the one that created it. The cursor must maintain the same isolation level throughout its lifetime.

This error occurs when the pg_dump client tool version is older than the PostgreSQL server you're backing up. PostgreSQL requires pg_dump to be the same version or newer than the target server.

This error occurs when PostgreSQL cannot find a table, view, or other relation with the specified name. The most common causes are case sensitivity issues, schema mismatches, table not being created, or incorrect connection to the database. Verify the table exists, check exact naming and case sensitivity, specify the correct schema, and ensure you're querying the right database.

This Foreign Data Wrapper error occurs when a column attribute number referenced in an FDW operation is invalid or out of range, typically after altering table structure without updating foreign table definitions.

This error occurs when using parameterized queries in PostgreSQL and the parameter placeholders ($1, $2, etc.) don't match the number of values provided. It typically happens when developers use prepared statements incorrectly, fail to provide all parameter values, or misconfigure their database driver. Ensure parameter counts align and use your driver's parameterized query API correctly.

The PostgreSQL "index does not exist" error occurs when attempting to drop, alter, rename, or reference an index that is not present in the database. Common causes include misspelled index names, case sensitivity issues, missing schema qualifiers, and attempting to drop already-removed indexes. Using IF EXISTS clauses and verifying index existence prevents this error.

This error occurs when a database user lacks permissions to access a sequence object. Sequences are separate database objects from tables, so granting table permissions does not automatically grant sequence access. The fix involves explicitly granting USAGE and UPDATE privileges on the sequence.

PostgreSQL throws SQLSTATE 2200T (invalid_xml_processing_instruction) when processing XML data that contains a malformed XML processing instruction. This error occurs when using PostgreSQL's XML functions like xmlpi() or when parsing XML data that includes processing instructions with invalid syntax, such as missing closing ?> tags or containing forbidden character sequences.

This error occurs when a user lacks the required privileges to access or modify a table. Fix it by granting appropriate permissions using the GRANT statement.

The PostgreSQL error "25005: no_active_sql_transaction_for_branch_transaction" occurs when attempting to create a branch transaction (using SAVEPOINT) without an active parent transaction. This happens when savepoint operations are executed outside of a transaction block or after a transaction has already been committed or rolled back.

A PostgreSQL function execution fails because the user lacks EXECUTE privilege. Grant the required permissions using GRANT EXECUTE to allow the user to call the function.

This error (code 28000) occurs when PostgreSQL denies access due to missing or incorrect authentication configuration in pg_hba.conf, invalid credentials, or authorization restrictions. Verify your connection credentials and pg_hba.conf settings to resolve it.

PostgreSQL raises HV021 when a foreign-data wrapper detects inconsistent descriptor information between the local foreign table definition and the remote server's metadata. This typically happens when column definitions, data types, or constraints mismatch after schema changes on either side. Reconciling the foreign table descriptor with the remote catalog resolves the inconsistency.

PostgreSQL requires the data directory to have restrictive permissions (0700 or 0750). This error appears when permissions are too permissive, typically after pod restarts in containers or when mounting volumes with incorrect ownership.

This error occurs when PostgreSQL attempts to authenticate a user role that hasn't been created in the database. The role must be explicitly created before it can be used for connections.

PostgreSQL throws SQLSTATE 2200S (invalid_xml_comment) when processing XML data that contains malformed XML comments. This error occurs when using PostgreSQL's XML functions or when parsing XML data that includes comments with invalid syntax, such as containing double hyphens (--) or not being properly closed with -->.

This error occurs when a PostgreSQL client disconnects abruptly without properly closing the connection, often due to network issues, timeout settings, or firewall interference. Fix it by configuring TCP keepalive settings, implementing connection pooling, and ensuring proper client-side connection handling.

This error occurs when a non-owner or non-superuser attempts to modify, drop, or comment on a PostgreSQL extension. Most commonly encountered during database dumps/restores or Rails migrations, it requires either ownership privileges or superuser permissions to resolve.

This replication error occurs when a standby PostgreSQL server's database system identifier doesn't match the primary server's identifier, indicating they are not properly related. This happens when the standby wasn't created from a backup of the primary.

PostgreSQL rejects connection attempts when authentication fails, pg_hba.conf denies the client, or the server misconfiguration prevents connections. This typically involves credential issues, network configuration, or permission problems.

PostgreSQL password authentication failures occur when credentials are incorrect, misconfigured, or the authentication method is incompatible. Verify your password, connection string, and pg_hba.conf settings to resolve.

PostgreSQL raises HV010 when a Foreign Data Wrapper (FDW) calls its API functions in the wrong order or repeats a step that should only happen once. This violates the FDW callback sequence defined in the SQL/MED standard, indicating a bug in the FDW extension code or improper state management during query execution.

The PostgreSQL 08P01 protocol violation error occurs when the client and server break the agreed wire protocol during communication. Fix it by aligning driver versions, checking SSL settings, and verifying network configuration.

The PostgreSQL error "42P11: invalid_cursor_definition" occurs when a cursor declaration contains invalid syntax, references non-existent tables or columns, or violates cursor definition rules. Cursors in PostgreSQL allow iterative processing of query results, but improper definition prevents their creation and requires correcting the cursor declaration.

This error occurs when a user lacks the required CONNECT privilege to access a PostgreSQL database. Grant the missing privileges using GRANT CONNECT or GRANT ALL PRIVILEGES to restore access.

SQLSTATE 22009 occurs when PostgreSQL encounters an invalid time zone offset or displacement value. This error typically appears when working with time zone-aware timestamps, interval arithmetic, or when converting between time zones with malformed offset values.

This error occurs when PostgreSQL rejects a login attempt due to incorrect credentials, misconfigured authentication settings, or a missing password. Common causes include wrong password, incorrect pg_hba.conf authentication method, or users created without passwords.

This error occurs when PostgreSQL cannot determine whether a transaction was committed or rolled back due to a connection loss. It typically indicates a network disruption between your application and the database server.

This error occurs when you attempt to connect to PostgreSQL while it is still initializing or recovering from an unexpected shutdown. Typically, waiting for the startup process to complete or restarting the database service resolves the issue.

This error occurs when PostgreSQL terminates a connection abnormally, typically due to server crashes, network issues, idle timeouts, or firewall interference. Fix it by checking server logs, adjusting TCP keepalive settings, and configuring proper timeout values.

This error appears when PostgreSQL is in the process of shutting down and rejects new connection attempts. It typically occurs during planned maintenance, restarts, or server failures. Fix by verifying the server status, waiting for the shutdown to complete, or investigating why an unexpected shutdown occurred.

The "FATAL: Ident authentication failed for user" error occurs when PostgreSQL authentication method is set to ident but the operating system username does not match the PostgreSQL database username. This typically affects local connections and requires changing pg_hba.conf to use password authentication instead.

PostgreSQL cannot determine which collation to use when comparing or sorting text values. This happens when multiple columns or expressions with different collations are combined without an explicit COLLATE clause.

The PostgreSQL 2F005 error occurs when a function declared to return a value executes without reaching a RETURN statement. This happens in PL/pgSQL functions that miss return paths, have conditional logic without default returns, or encounter exceptions before returning.

The 0F001 error indicates an invalid Large Object (LOB) locator specification in PostgreSQL. This SQL standard error typically occurs when attempting to use a LOB locator variable that does not represent a valid value or when accessing large objects outside of a transaction context.

PostgreSQL "permission denied for schema" error occurs when a user lacks necessary privileges to access or create objects within a schema. Especially common in PostgreSQL 15+ where public schema permissions changed, it requires granting explicit USAGE and CREATE privileges. Fix by using GRANT statements with appropriate permissions.

IAM authentication failure occurs when PostgreSQL cannot validate your identity through your cloud provider's IAM system. This typically affects AWS RDS and Google Cloud SQL users and requires proper configuration of authentication tokens, user roles, and SSL connections.

This error occurs when trying to create a PostgreSQL extension without superuser privileges. Most extensions require superuser permissions for security reasons, though some trusted extensions can be installed by database owners.

This error occurs when you attempt to connect to a PostgreSQL database that doesn't exist on the server. It commonly happens when psql tries to connect to a database with the same name as your OS user account, or when you specify an incorrect database name in your connection string.

This error indicates a general diagnostics exception in PostgreSQL without a more specific error code. It typically occurs when there are issues with diagnostic operations or exception handling in PL/pgSQL functions.

This error occurs when a CREATE DATABASE or ALTER DATABASE statement contains invalid syntax or parameters. Fix by verifying your database definition syntax and ensuring all options are valid.

This error occurs when the PostgreSQL server has reached its maximum concurrent connection limit (max_connections parameter). The server rejects new connection attempts to prevent resource exhaustion. Increase max_connections, implement connection pooling, or identify and close idle connections to resolve the issue.

PostgreSQL cannot find the data type you referenced in your query or CREATE statement. This error occurs when a custom type, enum, domain, or composite type is undefined, misspelled, in a different schema, or hasn't been created yet. Error code 42704 (undefined_object).

The PostgreSQL 'unterminated quoted string' error occurs when a SQL query contains a string literal that is missing its closing single quote. This is a parse-time syntax error that prevents the query from executing. Common causes include missing closing quotes, unescaped quotes within strings, or improper string literal formatting.

PostgreSQL foreign key violation (ERROR 23503) occurs when you try to INSERT, UPDATE, or DELETE a row that violates a foreign key constraint. This means the referenced value does not exist in the parent table, or you're trying to delete a parent row that still has referencing child rows. Fixing requires ensuring referential integrity by inserting parent records first or using appropriate constraint actions like CASCADE.

The PostgreSQL "syntax error at or near TOKEN" error occurs when the parser encounters an unexpected keyword, symbol, or delimiter during query parsing. Common causes include missing commas, mismatched parentheses, incorrect quote usage, reserved keywords used as identifiers, and clause ordering issues. Fixing requires carefully reviewing SQL syntax and ensuring proper structure.

This PostgreSQL error occurs when you try to insert or update a record with a value that already exists in a column with a unique constraint. Fix it by checking the constraint, handling duplicates with upsert, or resyncing sequences if using auto-increment columns.

This error occurs when PostgreSQL cannot find a column you're trying to reference in a SELECT, WHERE, ORDER BY, or other clause. Common causes include typos in column names, case sensitivity issues with quoted identifiers, missing table aliases in JOINs, or referencing a column that doesn't actually exist in the table.

This error occurs when an INSERT or UPDATE statement attempts to set a NULL value in a column declared with a NOT NULL constraint. PostgreSQL enforces data integrity by preventing null values in columns defined as NOT NULL. To fix this, provide a non-null value for the affected column or adjust the query to include all required fields.

The PostgreSQL "Unterminated dollar-quoted string" error occurs when a dollar-quoted string ($$...$$) is not properly closed, typically due to SQL client tools not understanding dollar quoting syntax and incorrectly splitting statements at internal semicolons. Dollar quoting is a PostgreSQL feature for writing string constants without escaping nested quotes, but many tools lack proper support for it.

PostgreSQL doesn't allow aggregate functions (COUNT, SUM, AVG, MAX, MIN) directly in the WHERE clause. This happens because WHERE filters rows before aggregation is computed. Use the HAVING clause instead to filter aggregated results.

This error occurs when PostgreSQL cannot convert a text value to the expected data type (integer, boolean, date, UUID, etc.). It means the string contains invalid characters or format for the target type.

This error occurs when a PostgreSQL client attempts to connect to a database but fails to provide authentication credentials. It happens when the user lacks a password, the .pgpass file is misconfigured, or environment variables aren't set properly.

A RESTRICT violation occurs when you try to delete or update a parent table row that is still referenced by rows in a child table with a RESTRICT foreign key constraint. The fix requires handling the referencing child rows first or modifying the constraint definition.

PostgreSQL throws this error when a date or timestamp string does not match the expected format. Fix it by ensuring your input dates are in the correct format (YYYY-MM-DD for dates, YYYY-MM-DD HH:MM:SS for timestamps) or by using TO_DATE() and TO_TIMESTAMP() functions with explicit format masks.

Error 22001 occurs when you try to insert or update a string value that exceeds the defined column length (e.g., a 15-character string in a VARCHAR(10) column). PostgreSQL rejects the data to protect data integrity, and you must either shorten the data or expand the column.

PostgreSQL error 42P21 occurs when the database cannot determine which collation to use for string comparison operations. This happens when comparing or joining columns with different collation settings, or when UNION/CASE statements combine strings that use incompatible sorting rules.

PostgreSQL error 22012 occurs when an SQL query attempts to divide a numeric value by zero. This runtime error stops query execution and rolls back the transaction. Use NULLIF(), CASE statements, or data filtering to prevent this error.

PostgreSQL error 22000 occurs when data fails validation during insertion, update, or type conversion. Common causes include string truncation, numeric overflow, or invalid value representations that violate column constraints.

The PostgreSQL 2F004 error occurs when a SQL routine attempts to read data in a context where such operations are restricted. This typically happens in functions or procedures that have data access limitations due to security constraints or incorrect function declarations.

This error occurs when PostgreSQL encounters characters that cannot be represented in the database's character encoding. Common causes include encoding mismatches between client and server, or attempting to insert Unicode characters into a limited encoding like LATIN1.

SQLSTATE 01006 is a warning that PostgreSQL raises when a REVOKE statement attempts to remove privileges that were never granted. The operation completes successfully but serves as a notice that no actual privilege changes occurred, helping you audit your permission management scripts.

PostgreSQL error 2200C occurs when escape characters are used incorrectly in SQL statements. Common causes include using backslash escapes without the E prefix or invalid Unicode escape sequences.

PostgreSQL error 22P03 occurs when binary data format is invalid or mismatched with the column type. This happens with bytea columns, COPY BINARY operations, or client driver encoding issues.

A NOT NULL constraint violation occurs when you try to insert or update a record with a NULL value in a column that requires a value. Learn how to identify the problematic column and fix the query.

The PostgreSQL COPY command failed because the input file format does not match the expected format. This typically occurs due to delimiter mismatches, encoding issues, or structural problems in the data file.

A floating point exception in PostgreSQL typically occurs due to division by zero or invalid arithmetic operations. This can be prevented by adding guards in your SQL queries to check for zero denominators before performing division.

PostgreSQL raises this error when JSON object constructors with UNIQUE constraints detect duplicate keys. Most often occurs with json() constructor, JSON aggregate functions, or when merging JSON objects.

This error occurs when using incorrect subscript syntax to access JSON or JSONB data in PostgreSQL. The subscript must be an integer for arrays or a string for objects, and the data type must match the operation.

SQLSTATE 55P04 occurs when PostgreSQL detects unsafe usage of a newly added enum value in a transaction that started before the enum was altered. This prevents data corruption by ensuring transactions see consistent enum definitions.

PostgreSQL enforces unique keys in JSON objects, especially with jsonb and PostgreSQL 15+ SQL/JSON functions. This error occurs when you try to create or construct a JSON object with duplicate keys. Ensure all keys in your JSON objects are unique.

The "invalid regular expression" error (code 2201B) occurs when PostgreSQL encounters malformed regex syntax. Common causes include unescaped special characters, unbalanced parentheses, invalid escape sequences, or PCRE-specific syntax incompatible with PostgreSQL's POSIX regex engine.

This error occurs when a SQL/JSON path expression tries to access an array element on non-array data. Resolve it by verifying your JSON structure matches the path expression and using jsonb_typeof() to check data types.

The PostgreSQL error "42P10: invalid_column_reference" occurs when a SQL statement references a column in an invalid context, such as using a column that doesn't exist in the current scope or referencing it incorrectly in subqueries, joins, or window functions. This syntax error prevents query execution and requires correcting the column references.

This error occurs when accessing a non-existent field in JSON data with strict mode enabled. Switch to lax mode or use error handling clauses to suppress or handle missing JSON members gracefully.

This error occurs when PostgreSQL encounters data that doesn't conform to UTF-8 encoding. Common causes include importing data from non-UTF8 sources, null bytes in text fields, or client/server encoding mismatches. Ensure data is properly encoded or use appropriate binary formats.

PostgreSQL throws this error when JSON_QUERY or JSON_VALUE receives multiple items but expects a single item. Use WITH WRAPPER clause or filter your JSON path to return exactly one item.

PostgreSQL error 22023 occurs when a parameter passed to a function or SQL command has an invalid value, incorrect data type, or is outside the expected range. Common causes include malformed timezone settings, wrong character encoding parameters, and type mismatches in function arguments.

PostgreSQL raises an array subscript error when accessing an array element with an invalid or out-of-bounds index. This commonly occurs when using multi-dimensional arrays or when index values exceed the array bounds, especially in PL/pgSQL functions.

PostgreSQL throws datetime field overflow (SQLSTATE 22008) when a date or time value is outside the valid range for its field. Common causes include invalid dates like "0000-00-00 00:00:00", incorrect formats, or timestamps with excessive precision.

This error occurs when PostgreSQL encounters an empty string in a context that requires a non-empty value, such as type casting or operations on specific columns. Fix it by validating input, using NULLIF to convert empty strings to NULL, or adjusting your schema constraints.

This error occurs when PostgreSQL cannot convert a character from the client encoding to the database encoding. Fix it by aligning encodings to UTF-8 or preprocessing data before import.

This error occurs when you attempt to insert or update a string value that exceeds the maximum length defined by a VARCHAR(n) or CHAR(n) column. PostgreSQL enforces strict length constraints that prevent oversized strings from being stored.

This error occurs when PostgreSQL cannot convert a value to the target data type due to incompatible characters or format. It commonly happens during type conversions with the CAST operator or :: syntax when the source data contains invalid characters for the target type.

This error occurs when a SQL string literal is missing its closing quote, causing PostgreSQL to treat the rest of the query as part of the string. Fix it by ensuring all quoted strings have matching opening and closing quotes.

This error occurs when performing numeric operations on JSON values that are not actually numeric types. Fix by validating JSON types before operations, using error-suppressing operators, or specifying proper error handling modes.

This error occurs when a JSON path expression in strict mode fails to match the expected structure of your JSON data. Using lax mode or handling errors with ON EMPTY/ON ERROR clauses resolves the issue.

PostgreSQL rejects malformed JSON when casting or storing invalid syntax. This error (SQLSTATE 22P02) occurs when JSON parsing fails due to structural issues, missing quotes, or invalid tokens.

This error occurs when a JSON_VALUE() function or similar SQL/JSON scalar function returns multiple items instead of the expected single value. It typically happens when your JSON path expression matches multiple array elements or objects.

The PostgreSQL 42P13 error occurs when creating or altering a function with invalid syntax, missing parameters, or conflicting definitions. This prevents the database from parsing and storing the function correctly, requiring syntax fixes and validation.

This error occurs when attempting to create a database with a name that already exists in your PostgreSQL cluster. Use IF NOT EXISTS or choose a different database name to resolve it.

A duplicate cursor error (SQLSTATE 42P03) occurs when attempting to declare a cursor with a name that already exists in the current session. Close the existing cursor before redeclaring it.

This PostgreSQL error occurs when invalid arguments are passed to the width_bucket() function, which is used for histogram calculations. The function requires numeric arguments with proper bounds and bucket counts that follow mathematical constraints.

PostgreSQL throws the duplicate column error (42701) when you attempt to add a column that already exists or specify the same column name multiple times. Fix it by checking existing columns, using aliases in joins, or leveraging IF NOT EXISTS clauses in migrations.

The PostgreSQL error "2D000: invalid_transaction_termination" occurs when a transaction is terminated incorrectly, such as attempting to COMMIT or ROLLBACK at an invalid point in transaction flow. This typically happens when transaction control statements are used improperly within stored procedures, functions, or application code.

This error occurs when using strict mode in SQL/JSON path expressions to access a non-existent JSON object member or array element. Switch to lax mode or add error handling clauses to suppress the error.

PostgreSQL throws 2200M (invalid_xml_document) when libxml2 rejects the payload passed to XMLPARSE, XMLTABLE, XML functions, or an xml column insert because the text is not a well-formed XML document. The parser wants a single root node and complete tag structure, so missing roots, stray text nodes, or bad syntax cause the query to fail before the server ever stores or evaluates the value.

PostgreSQL reports error 42P20 whenever a window function or window clause violates the SQL syntax rules that govern where window functions can appear or how their frames are defined. The parser and transformer reject invalid combinations such as window calls inside WHERE/JOIN filters, nested window functions, improper frame boundaries, or attempts to override a named window's partition/order definition.

PostgreSQL enforces a hard limit of 65,535 key-value pairs in JSON/JSONB objects. Exceeding this limit raises error 2203E. The fix involves restructuring your data to use nested objects or arrays instead of a single flat object.

SQLSTATE 01003 is a warning that PostgreSQL inherits from the SQL standard whenever a set function (aggregate) skips NULL inputs. The query still returns a result, but the warning flags that nulls were silently removed so you can decide whether the missing values were expected.

This error occurs when using PostgreSQL's JSON_VALUE function with a JSON path expression that returns an array or object instead of a scalar value. The JSON_VALUE function is designed to extract single scalar values, and will fail if the path expression points to a non-scalar result.

PostgreSQL raises this error whenever an external routine (C extension, FDW, or PL handler) signals a problem with a malformed SQLSTATE. The server enforces the SQLSTATE rules documented in the error-code appendix so that clients receive a predictable error protocol.

This PostgreSQL error occurs when you attempt to create a prepared statement with a name that already exists in the current session. The solution is to deallocate the previous statement or use a different name.

PostgreSQL throws this error when a query uses the same alias name for multiple columns, table joins, or expressions. Fix it by ensuring each alias is unique within the query scope.

The PostgreSQL error "39P03: event_trigger_protocol_violated" occurs when an event trigger function violates the expected protocol for event trigger execution. Event triggers are special triggers that respond to DDL (Data Definition Language) events like CREATE, ALTER, or DROP commands, and they must follow specific interface requirements.

The PostgreSQL error "25007: schema_and_data_statement_mixing_not_supported" occurs when attempting to mix schema modification statements (DDL) with data manipulation statements (DML) in contexts where they cannot be combined. This typically happens in prepared statements, certain transaction blocks, or when using specific PostgreSQL extensions that have restrictions on statement mixing.

PostgreSQL error 42710 occurs when attempting to create a database object (table, index, function, or sequence) that already exists with the same name in the same schema. This happens most commonly during migrations, deployments, or when running CREATE statements multiple times.

This error occurs when Liquibase detects a changeset identifier that has already been deployed to your PostgreSQL database. It happens when you try to re-run a migration that Liquibase has marked as executed, or when duplicate changesets are present in your changelog files.

PostgreSQL throws an ambiguous function error when it cannot determine which overloaded function to call due to unclear argument types or multiple matching candidates. Resolve this by using explicit type casts or qualifying function calls.

PostgreSQL cannot determine which table a column reference belongs to when multiple tables share the same column name. Qualify column names with table aliases to resolve the ambiguity.

This PostgreSQL error occurs when using the OFFSET clause with invalid row counts in SQL queries. The OFFSET clause skips a specified number of rows before returning results, but requires valid numeric arguments that don't exceed result set boundaries or violate SQL syntax rules.

The 2201B error occurs when PostgreSQL encounters malformed regex syntax. This typically involves unescaped special characters, unbalanced parentheses, or invalid escape sequences in pattern matching operations.

This warning occurs when PostgreSQL automatically pads a bit string with zeros to match the expected BIT(n) column length during explicit type casting.

This error occurs when attempting to create a replication origin with a name that already exists in the pg_replication_origin catalog, typically during logical replication setup or when manually creating origins.

This PostgreSQL error occurs when invalid arguments are passed to the SUBSTRING() function, which extracts parts of strings. The error typically happens when start positions or lengths are out of bounds, negative, or incompatible with the input string data type.

The "Triggered action exception" error occurs when a database trigger raises an explicit exception or fails during execution. This error aborts the SQL operation that fired the trigger and rolls back the entire transaction, indicating either a logic error in the trigger function or data that violates trigger-defined constraints.

PostgreSQL error 42883 occurs when a function call cannot be matched to any defined function with matching name and argument types. Common causes include typos, incorrect argument types, missing extensions, or schema path issues.

The "Prepared statement does not exist" error occurs when using connection poolers like PgBouncer or PgPool, where prepared statements are lost between transactions or connections. This can be fixed by disabling prepared statements, using binary parameters, or connecting directly to the database.

PostgreSQL throws "Invalid schema name" (error 3F000) when referencing a non-existent schema, using reserved names starting with pg_, or due to case sensitivity issues. Verify the schema exists, check naming rules, and use correct casing.

PostgreSQL raises error 38001 when SQL statements are attempted in contexts where they are explicitly prohibited, typically for security reasons. This occurs in security-definer functions, certain procedural language handlers, or when attempting to execute SQL in contexts that could bypass security controls.

This PostgreSQL error occurs when there's a conflict with escape characters in string literals, typically in COPY commands, E'...' strings, or when using backslashes as escape characters. The parser encounters ambiguous or conflicting escape sequences that it cannot resolve.

This error occurs when attempting to drop a PostgreSQL role that still has privileges granted on database objects. PostgreSQL prevents the role from being dropped to maintain security and ownership integrity.

PostgreSQL error 3D000 means you specified a database name that doesn't exist or is misspelled. Fix it by verifying the database name exists and checking your connection string.

PostgreSQL error 42804 occurs when trying to assign or compare values of incompatible data types. This requires explicit type casting using the :: operator or CAST() function to resolve the mismatch between columns and values.

PostgreSQL error 22P05 occurs when a character cannot be converted between database encodings, typically when moving data from UTF-8 to a single-byte encoding like WIN1252 or LATIN1. Resolve this by switching to Unicode drivers, fixing invalid characters, or adjusting client-side encoding settings.

PostgreSQL "certificate verify failed" is an SSL/TLS error that occurs when the client cannot verify the server's SSL certificate. This typically happens when root certificates are missing, outdated, or misconfigured. Download the appropriate root certificate and configure your client to use it with proper SSL mode settings.

This error occurs when attempting to use REFRESH MATERIALIZED VIEW CONCURRENTLY without a required unique index on the materialized view, or when the index includes a WHERE clause. Concurrent refresh requires a unique, unconditional index to safely perform the operation without locking the view.

This error occurs when PostgreSQL cannot start a new transaction because one is already active in the same XA transaction branch. It commonly happens in distributed transaction scenarios with multiple resources.

BEFORE row-level trigger functions must return either the modified row (NEW or OLD) or NULL to proceed. This error occurs when a trigger function fails to return a row value explicitly, preventing the database operation from completing.

PostgreSQL error 42883 occurs when you try to use an operator with incompatible data types. This commonly happens when comparing strings with integers or using operators on unsupported type combinations. Explicit type casting resolves this issue.

PostgreSQL fails to start when SSL is enabled but the server certificate file (server.crt) is missing, unreadable, or incorrectly configured. This error prevents any SSL connections from being established. Ensure the certificate file exists in the correct location with proper permissions.

This Foreign Data Wrapper error occurs when a query needs a dynamic parameter value at runtime but the FDW cannot obtain or convert it. Common with timestamp functions, date conversions, or runtime-evaluated expressions in queries against foreign tables.

PostgreSQL does not allow changing column data types in views using CREATE OR REPLACE VIEW. When the underlying table columns change type, the view definition becomes invalid. Drop and recreate the view with matching column types.

This error occurs when you call the currval() function before calling nextval() on a sequence in the current PostgreSQL session. The currval() function returns the last value generated by nextval() within the same session, and it requires that nextval() has been called at least once first.

PostgreSQL raises error 38000 when an external routine (such as a C function, external procedure, or foreign data wrapper function) encounters an exception during execution. This occurs when external code linked with PostgreSQL fails, throws an exception, or violates PostgreSQL's execution environment constraints.

PostgreSQL prepared statements can only contain a single SQL command. When executing multiple semicolon-separated commands with parameterized queries, PostgreSQL enforces this limitation. Execute statements separately or use alternative approaches to resolve this error.

PostgreSQL error 2BP01 prevents dropping tables that have dependent objects like foreign key constraints or views referencing them. To resolve this, either drop dependent objects first or use the CASCADE option to remove them automatically.

This error occurs when you try to reference a table from a different database using the three-part naming convention (database.schema.table). PostgreSQL does not support cross-database queries directly. Instead, use schemas within a single database or the postgres_fdw extension to connect to other PostgreSQL servers.

PostgreSQL raises error 2F000 when a SQL routine (function, procedure, or trigger) encounters a generic exception during execution. This catch-all error occurs for routine-level failures that don't fit into more specific error categories, typically indicating logic errors, constraint violations, or unexpected conditions within stored procedures or functions.

An invalid cursor state error (SQLSTATE 24000) occurs when attempting operations on a cursor that is not in the correct state, such as fetching from a closed cursor or operating on a cursor that was never opened. Fix it by ensuring the cursor is opened before use and properly managed throughout the transaction.

This error occurs when the .datetime() method in PostgreSQL jsonpath expressions receives a string that cannot be parsed as a valid date/time format. Fix it by ensuring ISO 8601 format, using the silent parameter, or specifying a datetime template.

PostgreSQL enforces a 268MB size limit on JSONB array elements to prevent memory issues. Split large arrays into multiple smaller arrays or normalize data into relational tables.

This error occurs when using PostgreSQL SQL/JSON functions like JSON_VALUE() or JSON_QUERY() and attempting to cast a JSON value to an incompatible SQL type. It typically indicates a type mismatch between the JSON content and the target data type.

SQLSTATE 22010 occurs when PostgreSQL receives an invalid indicator parameter value in a prepared statement or function call. Indicator parameters are used to signal NULL values in parameterized queries, and this error means the indicator value provided does not conform to SQL standards.

This error occurs when a JSON_VALUE() or jsonb_path_query() call in strict mode tries to extract a numeric value from a JSON path that doesn't contain a number or doesn't exist. Use ON ERROR/ON EMPTY clauses or switch to lax mode to handle missing numeric values.

PostgreSQL raises the duplicate function error (code 42723) when you try to CREATE a function with the same name and parameter types as an existing function. Use CREATE OR REPLACE FUNCTION to update existing functions or DROP the old one first.

The "duplicate table" error (SQLSTATE 42P07) occurs when you attempt to create a table that already exists in the database. Use CREATE TABLE IF NOT EXISTS to prevent this error.

PostgreSQL raises a duplicate schema error when you try to create a schema that already exists. Use CREATE SCHEMA IF NOT EXISTS or check if the schema is already present before creating it.

PostgreSQL throws an ambiguous column error when a column name exists in multiple tables without proper qualification. Qualify column names with table aliases or names in JOIN queries to resolve the error.

The "Ambiguous parameter" error occurs when PostgreSQL cannot determine which parameter or column you are referencing because the same name appears in multiple contexts. This happens when parameters have conflicting type expectations or when variables share names with table columns in functions.

PostgreSQL error 42703 occurs when a query references a column that doesn't exist in the table. This is usually caused by typos, case sensitivity issues, or schema changes.

PostgreSQL error 42P01 occurs when a query references a table that does not exist. This commonly happens due to misspelled table names, schema confusion, case sensitivity issues, or connecting to the wrong database.

PostgreSQL error 42P02 occurs when a prepared statement references a parameter placeholder like $1 but no actual value is supplied. Fix by providing all bind variables or removing unused placeholders.

Error 42704 occurs when a query references a table, column, type, or other database object that does not exist. This commonly happens due to typos, case sensitivity issues, or missing schema qualifiers.

PostgreSQL error 42846 occurs when attempting an incompatible type conversion. Fix it by using explicit CAST() or the :: operator to convert values to compatible types.

PostgreSQL cannot determine the data type of a parameter or value in your query. This typically occurs with untyped parameters, NULL values, or ambiguous function calls. Fix by adding explicit type casts using the :: operator.

PostgreSQL cannot determine which collation to use when comparing columns with conflicting implicit collations. Resolve by explicitly specifying a collation using the COLLATE clause.

This PostgreSQL error occurs when non-standard escape character sequences are used in PL/pgSQL code or SQL queries. The error indicates that escape sequences don't conform to PostgreSQL's standard escape syntax, often happening with Unicode escapes, hexadecimal escapes, or custom escape patterns in procedural code.

PostgreSQL raises HV00R when a foreign-data wrapper cannot locate a referenced table on the remote server. This typically occurs when querying a foreign table that has been dropped, renamed, or never existed on the remote side. Verifying the remote table existence and updating the foreign table definition resolves this error.

PostgreSQL collation mismatch errors occur when database collation settings no longer match the OS locale, typically after system upgrades. Fix by refreshing collation versions and reindexing affected databases.

PostgreSQL aborts transactions when errors occur, preventing further queries until explicitly rolled back. This happens because PostgreSQL enters an aborted state rather than continuing execution like some other databases.

PostgreSQL error 25001 occurs when a transaction is already active and prevents certain operations like DROP DATABASE or ALTER TYPE from executing. Commit or rollback the current transaction first to resolve this.

This error occurs when attempting to execute write operations (INSERT, UPDATE, DELETE) on a read-only transaction. Common causes include connecting to a read-only replica, hot standby server, or default_transaction_read_only setting enabled.

This error occurs when attempting to use TRUNCATE ONLY on a partitioned table, which is not allowed because partitioned tables are logical containers that hold no data themselves—all data resides in their child partitions.

PostgreSQL transaction timeout occurs when a transaction exceeds the configured time limit. This error prevents long-running operations and helps manage resource consumption by automatically terminating idle or overly long transactions.

This error occurs when you try to use a reserved system column name (like tableoid, ctid, xmin, or xmax) as a regular column name in PostgreSQL. System columns are automatically added to every table and cannot be redefined.

When a query fails in a PostgreSQL transaction, all subsequent commands are rejected until the transaction is rolled back. This occurs by design to maintain data consistency and requires explicit recovery using ROLLBACK or SAVEPOINT.

PostgreSQL terminates idle transactions to prevent locks and table bloat. Configure idle_in_transaction_session_timeout to set a maximum idle period, or disable it (0ms) for maintenance operations.

This warning appears when a PostgreSQL procedure returns multiple dynamic result sets using refcursors. It's informational, not an error, indicating that multiple cursors were opened and returned.

This PostgreSQL error occurs when CREATE TABLE or ALTER TABLE statements contain conflicting clauses, syntax errors, or violate table design rules like defining multiple primary keys or mixing incompatible table types.

This error occurs when PostgreSQL receives a value that doesn't match the UUID format (FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF). Common causes include empty strings, malformed UUIDs, or passing non-UUID data types to UUID columns.

A transaction rollback occurs when PostgreSQL automatically cancels all changes in a transaction block due to an error or constraint violation. Understanding the causes and recovery methods helps prevent data inconsistency and application crashes.

PostgreSQL error 25P01 occurs when attempting to commit, rollback, or use SAVEPOINT outside an active transaction block. This commonly happens when a transaction is prematurely terminated, the connection drops, or your application's transaction tracking is out of sync with the database. The fix involves ensuring transactions are properly started before attempting to end them.

This PostgreSQL error occurs when a SQL statement references a role (user or group) that doesn't exist, has an invalid name format, or when attempting unsupported operations on a role.

PostgreSQL raises HV000 whenever a Foreign Data Wrapper fails but the connector cannot classify the failure into a narrower SQLSTATE. It usually hides a remote service error, driver mismatch, or a network hiccup, so you need to follow the FDW logs both in PostgreSQL and on the foreign system to find the root cause.

PostgreSQL error 39P01 "Trigger protocol violated" occurs when a trigger function does not return the correct value type or structure. BEFORE triggers must return NULL or a row matching the table structure; AFTER triggers must also return a value. Ensure your trigger function is properly defined with the TRIGGER return type.

The initdb command fails with a permission denied error when it lacks write access to the data directory or its parent. This typically occurs due to incorrect directory ownership, file permissions, or volume mount issues in Docker/Kubernetes. Fix by ensuring proper ownership (postgres user), correct permissions (0700), and running initdb with appropriate privileges.

PostgreSQL raises error 22013 when a window function frame specification uses an invalid value for PRECEDING or FOLLOWING row offsets. The frame size must be a non-negative integer expression, evaluated at runtime, and cannot be negative or NULL. This error occurs during query execution when the computed offset violates these constraints.

PostgreSQL prevents you from directly changing a column's data type if that column is used in a view or rule dependency. You must drop the dependent view(s) first, alter the column, and then recreate them in a transaction.

PostgreSQL raises this error when a regular expression pattern exceeds internal complexity limits in the POSIX regex engine. This typically occurs with deeply nested patterns, excessive alternations, or very long character classes. Simplify the regex pattern or break it into multiple smaller queries to resolve this issue.

This error occurs when you attempt to create a foreign key constraint that references a column without a PRIMARY KEY or UNIQUE constraint, or when there is a mismatch in column count or data types between the referencing and referenced columns.

This error occurs in AWS RDS when attempting to modify parameters in a default parameter group, which is immutable. AWS restricts changes to default groups for safety. Create a custom parameter group instead and apply it to your RDS instance to resolve this issue.

The PostgreSQL error 42P09 (ambiguous_alias) occurs when a column reference in your query cannot be uniquely resolved because the same column name exists in multiple tables or aliases. This typically happens in JOIN operations, subqueries, or PL/pgSQL functions where the database cannot determine which table or alias the column belongs to.

PostgreSQL cannot acquire a necessary lock on a table because another transaction holds a conflicting lock. This error (code 55P03) typically occurs during DDL operations or when lock_timeout is exceeded.

PostgreSQL error 53000 occurs when the server cannot allocate necessary memory, disk space, or connection slots. This typically happens during large queries, bulk operations, or when system resources are exhausted, and requires adjusting configuration parameters or freeing up resources.

PostgreSQL error 42804 occurs when you attempt to insert, update, or assign a value of one data type to a column with an incompatible data type. This strict type checking requires explicit casting to resolve mismatches between the target column type and the value being assigned.

PostgreSQL error 40003 indicates the result of a SQL statement is unknown, typically due to network interruptions or connection failures during transaction execution. Recover by rolling back the failed transaction and retrying with proper error handling.

PostgreSQL does not support direct conversion of regular tables to partitioned tables. You must create a new partitioned table and migrate data using methods like ATTACH PARTITION or data copying.

This error occurs when Flyway attempts to migrate an existing PostgreSQL database that has tables but no Flyway schema history table. Flyway refuses to proceed to prevent data loss. Enable baselineOnMigrate or manually baseline the schema to resolve this.

This error occurs when PostgreSQL detects an operation targeting an object (sequence, constraint, index) that is not in the correct state. Most commonly appears when calling currval() or lastval() on a sequence before nextval() has been executed in the current session.

This error occurs when PostgreSQL encounters an invalid schema definition, typically during CREATE SCHEMA statements with syntax errors, reserved naming violations, or malformed schema commands. Common causes include using reserved "pg_" prefixes, invalid schema elements, or unsupported syntax in older PostgreSQL versions.

This error occurs in AWS RDS for PostgreSQL when a user without rds_superuser privileges attempts to install an extension. In RDS versions 13+, most extensions can be installed by users with CREATE database privileges, but some require elevated permissions. The fix depends on your RDS version and whether you can use delegated extension management.

PostgreSQL rejects new connections when the max_connections limit is reached. Fix this by tuning max_connections, implementing connection pooling with PgBouncer, or terminating idle sessions.

This error occurs when attempting to execute write operations in a read-only subtransaction or savepoint, or when the access mode conflicts between a parent transaction and its branch.

PostgreSQL encounters a disk full error when the file system runs out of available space. This prevents writes and can cause database shutdown. Immediate action is needed to free space or expand storage.

PostgreSQL autovacuum is performing an emergency VACUUM operation to freeze old transaction IDs and prevent transaction ID wraparound, which could cause database shutdown if not addressed.

PostgreSQL forbids window functions like ROW_NUMBER(), RANK(), or SUM() OVER() in WHERE clauses because window functions execute after WHERE filters. To filter based on window function results, compute them in a subquery or CTE first, then apply your WHERE condition in the outer query.

The "Cache lookup failed for type" error occurs when PostgreSQL cannot find a data type with a specific OID (Object Identifier) in its internal system catalog cache. This typically happens after types or schemas have been dropped and recreated while connections remain active. The cache mismatch causes queries and functions to fail until connections are reset or the application is restarted.

The "Cache lookup failed for function" error occurs when PostgreSQL cannot find a function in its system catalog (pg_proc). This typically happens after dropping and recreating functions while active connections reference the old function, or in cases of system catalog corruption.

The 39P02 error occurs when a set-returning function (SRF) or table function violates PostgreSQL's internal protocol requirements, typically when the function doesn't properly implement the expected return mode or fails to follow the correct sequence for returning multiple rows.

Heroku PostgreSQL plans have connection limits (20 for Essential, 120+ for Standard). When your application opens too many connections without reusing them, you hit this limit. Fix it by implementing connection pooling with pgBouncer, reducing your connection pool size, or upgrading your plan.

This error occurs when you attempt to calculate the logarithm of zero, a negative number, or provide an invalid base argument to PostgreSQL logarithmic functions like LOG(), LN(), or LOG10(). Logarithms are only mathematically defined for positive numbers.

PostgreSQL cannot write new data because the underlying filesystem has exhausted its storage capacity. Resolve this by freeing disk space, cleaning up temporary files, or increasing available storage.

PostgreSQL error 2F003 occurs when a SQL routine (function, procedure, or trigger) attempts to execute a statement that is prohibited in its current context, such as transaction control commands (COMMIT, ROLLBACK) or DDL statements within restricted function types.

PostgreSQL enforces a 100-argument limit on functions. This error occurs when calling functions like json_build_object() with more than 100 arguments, or when passing too many parameters to RAISE statements in PL/pgSQL. Solutions include using array-based approaches or composite data types.

The PostgreSQL COPY command rejects NULL representation strings that contain newline or carriage return characters to prevent data parsing errors. Use the default \N for text format or empty string for CSV format instead.

PostgreSQL error 27000 occurs when a trigger function attempts to modify data in a way that violates SQL standards or PostgreSQL trigger rules. This typically happens when a trigger tries to modify the same table that triggered it, creating recursion or constraint violations.

This error occurs when attempting to grant role privileges or permissions using a user account that lacks the necessary ADMIN OPTION on the role being granted, or when using GRANTED BY with insufficient privileges.

PostgreSQL configuration limit exceeded error (54000) occurs when a predefined system limit is surpassed, such as maximum table columns, function arguments, or query complexity. Fix by refactoring your schema or query design rather than adjusting compiled limits.

PostgreSQL forcibly closes connections that remain idle within an active transaction for too long. Adjust the timeout setting, optimize application code to minimize transaction scope, or disable it for maintenance operations.

The "Duplicate file" error (58P02) occurs when PostgreSQL encounters a file with the same name in a location where a new file is being created. This typically happens during tablespace creation or low-level file operations.

This error occurs when a PostgreSQL database's character encoding does not match the LC_CTYPE and LC_COLLATE locale settings. PostgreSQL requires that database encodings are compatible with the system locale. For non-C/POSIX locales, only one character set will work correctly with each locale.

PostgreSQL system errors (error code 58000) indicate unforeseen issues external to the database itself, such as hardware failures, disk problems, or file system corruption. Diagnosing requires checking logs, verifying disk space, and testing system resources.

PostgreSQL does not allow window functions to be nested inside the arguments of other window functions. If you need to apply multiple window functions sequentially, use a CTE or subquery to compute the inner window function first, then reference that result in the outer window function.

This error occurs when attempting to attach a table as a partition to a partitioned table, but the existing data in that table violates the partition constraints or range bounds you are defining.

PostgreSQL Error 58P01 occurs when the server cannot locate a required file. This commonly happens with missing extension control files, incorrect file paths in COPY commands, or file permission issues. Fixing it requires verifying file paths, checking permissions, and restarting the database service.

Liquibase checksum validation fails when a previously executed changeset has been modified since it was first applied to the database. The stored checksum no longer matches the calculated checksum of the current changeset, triggering a validation error. Resolve this by accepting the new checksum, using validCheckSum tags, or clearing outdated checksums.

An encoding mismatch occurs when the server encoding, client encoding, or database collation settings do not align, preventing proper character handling and data transfer. Resolve by standardizing encodings to UTF-8 across your PostgreSQL configuration.

PostgreSQL detects corrupted data when checksums are enabled. Recover by using failover replicas, replaying WAL from backups, or zeroing damaged pages with appropriate settings.

PostgreSQL index corruption causes queries to return incorrect results or fail. Rebuild the corrupted index using REINDEX to restore normal database operations.

This error occurs when attempting to reference a savepoint that does not exist, typically because it was never created, already released, or the parent transaction has ended.

PostgreSQL error 2F002 occurs when attempting to execute data-modifying statements (INSERT, UPDATE, DELETE) within a function or routine that is declared as read-only or has volatility restrictions preventing database modifications.

This error occurs when attempting to create a PostgreSQL logical replication subscription within a transaction block. PostgreSQL requires CREATE SUBSCRIPTION to run in autocommit mode when creating replication slots.

PostgreSQL operator intervention errors (SQLSTATE 57000) occur when a database administrator or system event interrupts normal database operations. These errors include admin shutdowns, query cancellations, and server unavailability. Identify the specific cause and reconnect or restart services to resolve.

PostgreSQL internal errors (SQLSTATE XX000) indicate the server reached an impossible state due to database corruption, software bugs, or hardware failures. Fix by checking logs, diagnosing corruption, and upgrading PostgreSQL to the latest minor version.

Flyway validation fails with a checksum mismatch when a migration file has been modified after it was successfully applied to the database. Flyway stores checksums of migration files and verifies them on startup to detect unauthorized changes. Fixing requires either reverting the migration file changes, using `flyway repair` to realign checksums, or manually updating the schema history table in development environments.

A query was canceled due to timeout, user request, or resource limits. Check statement_timeout settings and identify long-running queries to either optimize them or adjust timeout values.

PostgreSQL requires array literals to start with a curly brace {}. This error occurs when you use incorrect syntax like square brackets [] or omit the opening brace entirely. Fix it by using proper PostgreSQL array syntax or the ARRAY constructor.

PostgreSQL fails to start because the postmaster.pid lock file exists in the data directory, indicating a previous instance did not shut down cleanly. Remove the stale lock file after verifying no PostgreSQL processes are running.

The PostgreSQL "Setval: value out of bounds" error occurs when you try to set a sequence to a value that falls outside its defined minimum and maximum boundaries. This typically happens when setting a sequence to 0 (which violates the default MINVALUE of 1) or to a value below the sequence's custom MINVALUE. Fix it by checking the sequence's bounds and using appropriate values.

When dropping a PostgreSQL database fails or was completed unexpectedly, it usually means the database is still in use or recovery incomplete. Learn how to safely drop databases and recover from failed drop operations.

A query exceeded the allowed execution time. Configure statement_timeout, optimize slow queries with indexes, monitor lock contention, and adjust timeout settings based on query complexity.

PostgreSQL intentionally refuses to run as the root user for security reasons. Switch to an unprivileged user (typically postgres) to start the database server successfully.

Window functions like ROW_NUMBER(), RANK(), and DENSE_RANK() cannot be used directly in WHERE clauses because they are evaluated after the WHERE clause filters are processed. This limitation exists due to SQL's logical order of operations. Use a CTE (Common Table Expression) or subquery to compute window functions first, then filter in the outer query.

PostgreSQL rejects configuration parameters with unrecognized or unsupported values during startup or connection. This typically affects locale, timezone, or text search settings.

Your AWS RDS PostgreSQL instance has exhausted its allocated storage capacity. Resolve this by increasing storage, enabling autoscaling, or removing unnecessary data. Immediate action is required to prevent database unavailability.

PostgreSQL error 57014 occurs when a query exceeds the configured statement_timeout limit and is automatically terminated. This protects the server from runaway queries. Increase the timeout, optimize the query, or check for locks causing delays.

PostgreSQL config file errors occur when there are syntax mistakes or invalid parameters in postgresql.conf. These prevent the server from starting and can be fixed by reviewing log messages and validating configuration syntax.

The "malformed array literal" error in PostgreSQL occurs when array values are provided in incorrect syntax. PostgreSQL requires arrays to be enclosed in curly braces with proper comma separation and quoted elements. Common causes include using JSON syntax instead of PostgreSQL syntax, missing quotes around special characters, and data type mismatches. Fixing requires proper array formatting according to PostgreSQL conventions.

PostgreSQL idle session timeouts terminate inactive database connections to prevent lock accumulation and table bloat. Learn how to configure and troubleshoot idle_session_timeout and idle_in_transaction_session_timeout parameters.

This error occurs when you try to TRUNCATE a table that is referenced by another table through a foreign key constraint. TRUNCATE is much faster than DELETE but cannot proceed if child tables have references. Use CASCADE to truncate all related tables together, truncate tables in dependency order, or temporarily disable constraints.

PostgreSQL error 57P03 occurs when the server cannot accept connections because it is starting up, shutting down, or in recovery mode. This is typically temporary and resolves once the server completes its startup or recovery process.

This error occurs when your parameterized SQL query references a placeholder like $1 or $2, but the corresponding parameter value was not provided when executing the statement. This is typically a binding mismatch between your application code and the prepared statement.

This error occurs when a trigger updates the same table that triggered it, causing infinite recursion until PostgreSQL hits the stack depth limit. Fix it by adding conditional checks or using pg_trigger_depth() to prevent the trigger from re-executing on its own updates.

PostgreSQL crash shutdown (57P02) occurs when the server crashes and terminates all client connections during recovery. The server automatically restarts and replays the write-ahead log (WAL) to restore data integrity.

This error occurs when attempting to modify a PostgreSQL configuration parameter that cannot be changed at runtime. Most parameters require server restart or configuration file changes rather than SET commands.

PostgreSQL aborts statements that wait too long for locks when lock_timeout is configured. Adjust the timeout value or resolve blocking queries to fix this error.

Serialization failures occur when concurrent transactions conflict in PostgreSQL's Serializable or Repeatable Read isolation levels. Retrying the complete transaction from the beginning is the recommended fix.

PostgreSQL aborts transactions when data violates constraints like unique keys, foreign keys, or CHECK rules. Learn to identify which constraint failed, fix data conflicts, and use deferrable constraints to prevent transaction rollbacks.

This error occurs when PostgreSQL cannot find a custom type referenced in a function, procedure, or variable declaration. Common causes include missing schema qualification of custom types, incomplete migrations, enum type naming mismatches, or using non-PostgreSQL-compatible types like STRING instead of TEXT.

The PostgreSQL error 55006 (object_in_use) occurs when you attempt to drop or modify a database object that is currently being accessed by another session. Terminate conflicting connections or wait for the object to become available.

This error occurs when PostgreSQL is in recovery mode (e.g., on a Hot Standby replica), which restricts write operations. The database must either complete recovery or be promoted to primary mode to execute write commands.

A deadlock occurs when two or more transactions wait for each other to release locks, creating a circular dependency. PostgreSQL automatically detects and terminates one transaction to break the deadlock. Fix it by ensuring transactions always access rows in a consistent order.

PostgreSQL runs out of shared memory when the lock table exceeds capacity, typically due to excessive table locking or high concurrency. Increase max_locks_per_transaction or adjust connection settings to resolve.

PostgreSQL enforces a hard limit of 1,600 columns per table. This error occurs when you exceed that limit or hit the 1,664-column tuple limit in SELECT statements. Redesign your schema using arrays, JSON, or table partitioning.

PostgreSQL raises error 54000 when a query or schema surpasses built-in limits such as maximum columns per table, index key size, or expression nesting depth. Resolve by restructuring your schema, simplifying queries, or breaking down large operations.

Stack depth limit exceeded errors occur when PostgreSQL query execution exceeds the maximum call stack depth. This typically happens with recursive triggers, large IN clauses, or deeply nested queries. The fix depends on the root cause and may involve restructuring queries, preventing trigger recursion, or adjusting configuration parameters.

PostgreSQL error 3B000 indicates a general savepoint exception, typically occurring when attempting to rollback or release a savepoint that no longer exists. This commonly happens in ORMs when transaction state becomes desynchronized.

PostgreSQL raises error 54001 when a query exceeds internal planning complexity limits due to excessive joins, nested subqueries, or deeply nested expressions. Break the query into smaller parts using temporary tables or CTEs to resolve this.

PostgreSQL encounters file name limits when identifiers exceed 63 bytes. This typically affects table names, column names, or auto-generated sequence names. Shortening identifiers to comply with PostgreSQL's naming constraints resolves the issue.

PostgreSQL I/O errors occur when the database cannot read or write data to disk, typically due to network issues, disk space problems, or hardware failures. Diagnosis involves checking connectivity, disk space, and PostgreSQL logs.

PostgreSQL admin shutdown (error code 57P01) occurs when an administrator or process initiates a server shutdown. This prevents new connections and terminates existing sessions, typically during maintenance or due to system signals.

This error occurs when inserting data into a partitioned PostgreSQL table when no child partition exists for the data's values. With declarative partitioning, data is routed to child partitions based on constraints, and if a matching partition doesn't exist, PostgreSQL rejects the insert. Create missing partitions ahead of time or use automatic partition management to resolve this.

The PostgreSQL "COPY delimiter must be a single character" error occurs when you try to specify a multi-character or multi-byte delimiter in a COPY command. PostgreSQL only accepts single one-byte characters as delimiters. This error typically appears when copying data from files with custom delimiters, and requires either changing your delimiter or pre-processing your data.

VACUUM is a PostgreSQL maintenance command that cannot run inside a transaction block. This error occurs when your connection has an active transaction. Enable autocommit mode or commit before running VACUUM.

PostgreSQL "fixing permissions on existing directory" error occurs when initdb cannot change permissions on the PGDATA directory to the required security settings. This happens due to directory ownership issues, insufficient privileges, or containerized environments with volume mount problems. Fix by ensuring the postgres user owns the directory and has appropriate permissions before running initdb.

PostgreSQL prevents automatic vacuuming of temporary tables since they are session-specific. Manual VACUUM calls within the same session are allowed, or you can use TRUNCATE for faster cleanup without requiring maintenance.

PostgreSQL error 25006 occurs when your session attempts to write to the database while in read-only mode. Read-only mode can be enabled at the database, session, or transaction level, preventing any INSERT, UPDATE, DELETE, or DDL operations. Disable read-only mode or connect to the primary server to resolve this.

PostgreSQL raises this error when you attempt a write operation (INSERT, UPDATE, DELETE, CREATE, etc.) on a standby/replica server that is in recovery mode. Only the primary/master server accepts write transactions. Route write operations to the primary server to resolve this.

Azure Database for PostgreSQL enters read-only mode during planned maintenance to minimize downtime. This occurs when a HA failover transitions the standby to primary or when storage reaches critical thresholds. Applications attempting write operations receive "ERROR: cannot execute INSERT/UPDATE/DELETE in a read-only transaction".

PostgreSQL parameters with "postmaster" context cannot be changed without restarting the server. Learn how to identify restart-required parameters, apply changes correctly, and verify pending restarts.

PostgreSQL connection failures occur when the database server is unavailable, misconfigured, or unreachable. Fix it by verifying the service is running, checking network connectivity, and validating authentication settings.

PostgreSQL "Cannot attach partition" error occurs when ALTER TABLE ... ATTACH PARTITION fails due to schema mismatches, constraint violations, or overlapping partition bounds. Ensure column compatibility, add matching CHECK constraints before attaching, and verify partition bounds do not overlap.

PostgreSQL cursor error 34000 occurs when code attempts to use, fetch from, or close a cursor that has not been declared, has been closed, or exists outside the current transaction scope. Declare the cursor within the same transaction, use WITH HOLD for cross-transaction access, or ensure the cursor is still open.

WAL streaming failures in PostgreSQL replication occur when standby servers cannot connect to replication slots or when slots are missing. Common causes include deleted replication slots, case sensitivity issues, or reaching the maximum number of replication slots.

PostgreSQL cancels statements that exceed the lock_timeout waiting for locks on database objects. This error indicates lock contention—adjust the timeout, resolve blocking queries, or optimize transaction isolation to fix it.

PostgreSQL "cursor already exists" error occurs when attempting to declare or open a cursor with a name that is already in use within the same transaction or session. This commonly happens in PL/pgSQL functions called multiple times or when cursors are not properly closed. Fix by explicitly closing and deallocating cursors, or using set-based operations instead of manual cursor management.

The "chmod: changing permissions: Operation not permitted" error occurs when PostgreSQL fails to change file permissions during initialization, typically in Docker containers or when using NFS volumes with root_squash enabled. Fix by adjusting volume permissions, using Docker named volumes instead of bind mounts, or configuring NFS properly.

This error occurs when PostgreSQL replication or logical decoding tries to use a replication slot that doesn't exist on the server. It commonly happens when slot names are misspelled, slots are dropped without updating configuration, or when connecting to the wrong database instance during replication setup.

This message appears when PostgreSQL's autovacuum cannot acquire the required lock on a table. Usually harmless if occasional, but frequent occurrences indicate long-running transactions or conflicting operations blocking maintenance.

PostgreSQL standby server fails to start in hot standby mode when its max_connections setting is lower than the primary server. This occurs because the standby needs to allocate internal structures (KnownAssignedXIDs and lock tables) large enough to handle the maximum snapshot from the primary.

The PostgreSQL "Could not determine data type of parameter" error (SQLSTATE 42P18) occurs when PostgreSQL cannot infer the data type of a prepared statement parameter from its context. This typically happens when using NULL values, comparing with IS NULL, or using parameters in polymorphic expressions without explicit type casting. Fixing requires explicitly casting the parameter to the expected type.

This streaming replication error occurs when a standby server requests a WAL segment that has been deleted from the primary server. It indicates the standby has fallen too far behind and cannot catch up without rebuilding or using WAL archiving.

The "too many rows" error (P0003) occurs in PL/pgSQL when a SELECT INTO STRICT statement returns multiple rows instead of exactly one. Fix it by adding LIMIT 1, tightening WHERE clauses, or removing STRICT.

PostgreSQL prevents detaching a partition when active transactions or queries are accessing the partitioned table. This happens because the DETACH operation needs locks that conflict with running queries. Use DETACH PARTITION CONCURRENTLY (PostgreSQL 14+) or wait for transactions to complete.

PostgreSQL cannot find a table or index by its internal Object ID (OID), usually due to dropped tables, replication issues, or system catalog corruption. This critical error indicates missing or inconsistent database objects that require investigation and repair.

PostgreSQL automatically closes idle sessions based on the idle_session_timeout parameter, typically set for interactive users. This error occurs when a session has been idle (not running queries) for longer than the configured timeout duration.

System catalog reindexing is restricted in PostgreSQL. This error occurs when attempting concurrent reindexing of system catalogs or when system indexes become corrupted. Recovery requires specific techniques depending on the severity of corruption.

This error occurs when you attempt to create a database with CREATE DATABASE but a database with that name already exists. PostgreSQL does not support the IF NOT EXISTS clause for databases, so you must either drop the existing database, use a workaround query, or choose a different database name.

This error occurs when PostgreSQL encounters a reference to an object (table, schema, column, function, index, or view) that doesn't exist or cannot be found in the current context. Common causes include case sensitivity issues with quoted identifiers, typos in object names, wrong schema references, or objects that have been dropped or renamed.

Index creation fails due to deadlocks, constraint violations, lock timeouts, or disk space issues. Identify the root cause and drop any invalid indexes before retrying the CREATE INDEX operation.

This error occurs when you attempt to use a relation (table or view) as a composite type in a context where PostgreSQL expects a stand-alone composite type. It commonly happens when using table rows in function arguments, array constructors, or type conversions without proper syntax.

This error occurs when you attempt to create a PostgreSQL role (user account) that already exists in the database. Unlike CREATE TABLE, CREATE ROLE has no IF NOT EXISTS clause, so duplicate attempts fail. There are several solutions using PL/pgSQL blocks or conditional checks.

The "could not create unique index" error during pg_restore occurs when restoring data contains duplicate values that violate unique constraints. Resolve by identifying duplicate data, fixing the source, or using safe restoration techniques.

This error occurs when trying to create a unique index on a table that contains duplicate values in the indexed column(s). PostgreSQL refuses to create the index because existing data violates the uniqueness constraint. Fixing requires finding and removing duplicates before creating the index.

PostgreSQL error 34000 occurs when you reference a cursor that does not exist, has not been declared, or is not accessible in the current scope. Ensure the cursor is declared before use and accessed within the same transaction where it was created.

This error occurs during database backup when PostgreSQL terminates the pg_dump connection prematurely. Common causes include idle transaction timeouts, network interruptions, statement timeouts, and firewall issues. Check server logs and adjust timeout parameters to resolve.

This error occurs when you try to query a materialized view that was created with the WITH NO DATA clause but has never been populated. PostgreSQL requires the underlying query to be executed and the results stored before the view can be queried. Fix it by running REFRESH MATERIALIZED VIEW.

The NTILE() window function requires a positive integer argument representing the number of buckets. Error 22014 occurs when you pass an invalid argument type or value, such as zero, negative numbers, or non-integer types.

A PostgreSQL sequence has reached its maximum value, preventing new ID generation. This occurs when SERIAL columns exhaust their 4-byte integer range (~2.1 billion). Fix by altering the sequence to BIGINT or using CYCLE mode.

The "Must be owner of table" error occurs when a user attempts to alter, drop, or modify a table they do not own. Only the table owner (or superuser) can perform schema modifications on a table in PostgreSQL.

PostgreSQL error 42501 "insufficient privilege" occurs when a user attempts an operation without the necessary permissions on a database object. This role-based access control error requires granting appropriate privileges via GRANT statements.

The reserved name error occurs when using PostgreSQL reserved keywords as column or table names without proper quoting. PostgreSQL distinguishes between reserved and non-reserved keywords, and reserved words cannot be used as identifiers unless wrapped in double quotes.

PostgreSQL enforces a 63-character maximum length for all identifiers (table names, column names, index names, etc.). When you exceed this limit, PostgreSQL truncates the identifier silently, which can cause duplicate name errors or missing references when your application expects the full name.

This error occurs when PostgreSQL encounters an identifier (table name, column name, function name, etc.) that violates naming rules. Identifiers must start with a letter or underscore, contain only alphanumeric characters and underscores, and be 63 characters or fewer. Reserved keywords used as identifiers without proper quoting also trigger this error.

A check constraint violation occurs when you attempt to insert or update data that doesn't meet the boolean condition defined by a CHECK constraint on a table column. This is PostgreSQL's way of enforcing data integrity rules at the database level.

The "Numeric value out of range" error occurs when a numeric value exceeds the valid range for its data type. This typically happens when inserting large numbers into INTEGER/BIGINT columns or when NUMERIC/DECIMAL precision is insufficient.

Replication slots become inactive when the connected replica or client disconnects, causing PostgreSQL to retain WAL files indefinitely. This leads to disk space bloat and prevents autovacuum from cleaning dead tuples. Reconnect the subscriber or safely drop unused slots.

The "no data found" error occurs when a PL/pgSQL SELECT INTO STRICT statement returns zero rows. Handle it using the FOUND variable or catch the NO_DATA_FOUND exception in your stored procedures.

PostgreSQL cannot locate the required .control file for an extension. This happens when extension packages are missing or not properly installed on your system.

PostgreSQL rejects INSERT or UPDATE operations when a string value exceeds the defined length limit of a VARCHAR(n) column. This error occurs when you attempt to store a value longer than the maximum characters specified for that column.

Assert failures indicate internal consistency check violations in PostgreSQL, typically caused by data corruption, software bugs, or hardware issues. Check server logs, update PostgreSQL, and isolate the cause by testing extensions and hardware.

RAISE EXCEPTION is a PL/pgSQL statement for throwing custom errors in stored procedures and functions. Understanding proper syntax and usage prevents compilation errors and ensures transactions abort correctly when validation fails.

This error occurs when PostgreSQL cannot find a specified role (user account) in the database. It commonly happens during initial setup when the default postgres role hasn't been created, or when referencing a role that was never created or was accidentally dropped.

This error occurs when PostgreSQL rejects a login attempt due to incorrect credentials, misconfigured authentication settings, or missing passwords. Verify your credentials and pg_hba.conf configuration to resolve it.

PL/pgSQL errors occur when stored procedures, functions, or triggers contain syntax errors, type mismatches, or runtime exceptions. Fix them by validating RAISE statement syntax, checking parameter counts, and using GET STACKED DIAGNOSTICS for debugging.

PostgreSQL is warning that autovacuum has fallen behind in freezing old transaction IDs. This warning appears when the database is approaching transaction ID wraparound. You must run VACUUM soon to freeze old rows and prevent data corruption.

PostgreSQL enters read-only mode when transaction ID (XID) wraparound is imminent to prevent data corruption. This happens when autovacuum falls behind freezing old transactions, and you must run VACUUM immediately to restore write access before data loss occurs.

This PostgreSQL error occurs when a column definition specifies invalid length, precision, or scale attributes. Common causes include incorrect VARCHAR lengths, incompatible numeric precision/scale combinations, and invalid constraint specifications.

PostgreSQL extensions must have their supporting files installed on the system before you can use CREATE EXTENSION to load them into a database. This error occurs when the extension control file is missing or the extension package is not installed.

Foreign data wrapper (FDW) errors occur when connecting to remote data sources. Common causes include missing extensions, misconfigured servers, invalid credentials, or missing handler functions. Fix by installing postgres_fdw, verifying server configuration, and ensuring proper user mappings.

The PostgreSQL "syntax error at or near UNION" occurs when a UNION query is malformed, typically due to ORDER BY or LIMIT clauses appearing before UNION, mismatched column counts, incompatible data types, or missing parentheses around subqueries. Fixing requires understanding proper UNION syntax and ensuring all SELECT statements match in structure.

This error occurs when PostgreSQL cannot find a required extension. The extension files may not be installed, or they are not available in the system. Most commonly, you need to install the extension using CREATE EXTENSION or ensure the required packages are installed on your system.

A foreign key constraint violation occurs when you try to insert, update, or delete a row that breaks the relationship between parent and child tables. The fix depends on whether you're inserting orphaned records, deleting referenced rows, or loading data in the wrong order.

PostgreSQL "Could not connect to server: No such file or directory" occurs when the client cannot find the Unix domain socket file needed to connect locally. Common causes include PostgreSQL not running, mismatched socket paths between client and server, permission issues, or leftover postmaster.pid files blocking startup. Fixing requires restarting the server, verifying socket locations, and checking permissions.

The pg_dump utility lost its database connection mid-backup, usually due to network issues, server restarts, or timeout settings. Check server status, verify network connectivity, and adjust timeout parameters.

The "FATAL: Ident authentication failed for user" error occurs when PostgreSQL cannot authenticate a connection using ident authentication. This happens when the OS username does not map to the requested database user, or the ident server is unavailable. Fixing requires either switching to password authentication in pg_hba.conf or configuring proper user mappings in pg_ident.conf.

PostgreSQL "permission denied for schema" error occurs when a user lacks necessary privileges to access or create objects within a schema. Especially common in PostgreSQL 15+ where public schema permissions changed, it requires granting explicit USAGE and CREATE privileges. Fix by using GRANT statements with appropriate permissions.

This error occurs when a SQL query references a column that PostgreSQL cannot find in the table or view being queried. Common causes include case sensitivity issues with quoted column names, typos, using column aliases incorrectly, or missing table joins.

When CREATE INDEX CONCURRENTLY fails, PostgreSQL leaves behind an invalid index that consumes resources without providing query benefits. You must identify and remove the invalid index, then resolve the underlying cause before retrying index creation.

PostgreSQL indexes can become corrupted due to hardware failures, software bugs, or unexpected data issues. Use REINDEX or CREATE INDEX CONCURRENTLY to rebuild the corrupted index and restore database integrity.

pg_restore only works with binary or directory format dumps, not plain text SQL files. Use psql to restore text dumps or recreate dumps using pg_dump with the -Fc (custom) format flag.

This error occurs when PostgreSQL is performing recovery after an improper shutdown or when WAL control functions are executed on a standby/replica server. Most cases resolve automatically once recovery completes.

Your PostgreSQL sequence has exhausted its maximum value and can no longer generate new IDs. This typically happens with 32-bit integer sequences that reach 2.1 billion values. Fix it by using 64-bit sequences or altering the sequence to use a larger data type.

PostgreSQL "Connection does not exist" error occurs when a client tries to use or reference a connection that has been closed, terminated, or never established. Common causes include connection timeouts, server restarts, pooling misconfiguration, and referencing non-existent connections. Fixing requires verifying connection parameters, checking server status, and properly managing connection pools.

Peer authentication failed occurs when PostgreSQL tries to authenticate a connection using peer authentication (Unix socket) but the system username does not match the database username. Change the authentication method in pg_hba.conf or connect via TCP with a password.

An exclusion constraint violation occurs when you attempt to insert or update data that conflicts with an existing row according to the constraint's comparison rules. Exclusion constraints prevent overlapping or conflicting values using operators like equality or range overlap.

Connection exceptions in PostgreSQL occur when the client fails to establish or maintain a TCP/IP connection to the database server. This can happen due to the server not running, network issues, firewall blocking, or incorrect connection parameters.

PostgreSQL cannot start because the pg_version file is missing from the data directory. This typically occurs during upgrades, after data directory corruption, or when using an improperly initialized database cluster.

PostgreSQL collation errors occur when you reference a collation that is not available on your system. This typically happens after OS upgrades, during database migrations, or when using locale settings that are not installed. Check available collations and install missing locales to resolve the issue.

This error occurs when PostgreSQL's parser reaches the end of a statement unexpectedly. It typically indicates incomplete SQL syntax, missing parentheses, unclosed quotes, or incorrect parameter placeholders.

The "initdb: directory exists but is not empty" error occurs when trying to initialize a new PostgreSQL database cluster while the data directory already contains files. This is a safety feature to prevent accidental data loss. The error can be fixed by using an empty directory, removing existing files, or specifying a different initialization directory.

PostgreSQL connection refused error occurs when a client cannot establish a connection to the database server. This typically happens when the server is not running, not listening on the expected port, or has firewall/network restrictions.

PostgreSQL "Connection refused" error occurs when the client cannot establish a TCP connection to the server, typically because the PostgreSQL service is not running, not listening on the expected port, or network/firewall restrictions block the connection. Common fixes include starting the PostgreSQL service, verifying listen_addresses configuration, and checking firewall rules.

This PostgreSQL error (ERROR 23505) occurs when an INSERT or UPDATE operation tries to add a value that already exists in a column with a unique constraint or primary key. Common causes include out-of-sync sequences, duplicate data, or concurrent inserts. Fixing requires identifying the constraint, checking for existing duplicates, or using INSERT...ON CONFLICT.

This error occurs when you attempt to connect to a PostgreSQL database that doesn't exist on the server. It commonly happens when psql tries to connect to a database with the same name as your OS user account, or when you specify an incorrect database name in your connection string.

PostgreSQL connection failure occurs when a client cannot establish a connection to the database server. This can happen due to the server being down, incorrect connection parameters, network issues, or authentication problems.

PostgreSQL terminates connections unexpectedly due to server crashes, network timeouts, or configuration issues. Fix by checking server logs, enabling TCP keepalives, and verifying network stability.

PostgreSQL reaches its maximum allowed connections and reserves the remaining slots for superusers only. Regular applications cannot connect and receive this error when all available non-reserved connection slots are in use. This typically occurs due to application connection leaks, insufficient max_connections setting, or high traffic without proper connection pooling.

The 'FATAL: the database system is in recovery mode' error occurs when PostgreSQL is recovering from an unexpected shutdown, crash, or operating as a read-only standby/replica server. This typically happens after server restarts, crashes, or during replication scenarios.

This error occurs when PostgreSQL cannot find a table, view, or other relation with the specified name. It's usually caused by schema issues, case sensitivity problems, typos, or incorrect database connections. Fix by verifying the table exists, checking exact naming and case, specifying the correct schema, or adjusting search_path settings.

This fatal error occurs when PostgreSQL cannot allocate enough memory to execute a query or operation. Common causes include undersized work_mem settings, high concurrent connections, inefficient queries, and insufficient system RAM.

This error occurs when you attempt to insert or query a UUID column with a malformed value. PostgreSQL expects UUIDs in the standard 8-4-4-4-12 hexadecimal format, and will reject any value that doesn't match valid UUID syntax.

This error occurs when the number of parameters you bind to a prepared statement does not match the number of placeholders in the query. It usually happens when parameter placeholders ($1, $2) are accidentally quoted or when there's a mismatch between your prepared statement definition and the bind call.

This error occurs when you attempt to use GET STACKED DIAGNOSTICS outside of an exception handler block in PL/pgSQL. GET STACKED DIAGNOSTICS can only be called within an EXCEPTION WHEN clause to retrieve diagnostic information about the current exception.

The NTH_VALUE window function received an invalid argument for the row position parameter. The second argument must be a positive integer greater than zero.

Cardinality violation occurs when a query returns multiple rows in a context that expects a single row, such as in a subquery used with comparison operators or in an ON CONFLICT DO UPDATE statement.

The XML data being processed is malformed or contains invalid structures that the PostgreSQL XML parser cannot handle. This commonly occurs with DOCTYPE declarations, oversized text nodes, or special characters in COPY operations.

SQLSTATE 22022 occurs when an indicator variable or parameter is not large enough to hold the value being returned from a query or stored procedure. This typically happens in embedded SQL or driver-level parameter handling where indicator parameters are used to signal NULL values or data length information.

PostgreSQL error 22019 occurs when an invalid escape character is used in a LIKE pattern or string literal. This typically happens when the escape character in a LIKE ESCAPE clause is longer than one character or when backslash escapes are used incorrectly.

SQLSTATE 01007 is a warning that PostgreSQL raises when a GRANT statement attempts to assign privileges that you don't have authority to grant. The operation completes but signals that the requested privilege was not actually granted, helping you identify permission management issues in your scripts.

PostgreSQL raises HV007 when a foreign-data wrapper encounters a column name that does not exist on the remote data source. This typically occurs due to case sensitivity mismatches, incorrect column_name mappings, or remote table schema changes. Verifying column names and updating the foreign table definition to match the remote schema resolves the error.

The PostgreSQL 42P14 error occurs when creating a prepared statement with syntax errors, mismatched parameter types, or invalid SQL. This prevents the server from parsing and caching the prepared statement, requiring corrections to the SQL definition.

This PostgreSQL error occurs when the TRIM() function receives invalid arguments or data types. The error happens when TRIM(), LTRIM(), or RTRIM() are called with incompatible parameters, typically when the character argument is invalid or when passing non-string data types that cannot be trimmed.

The PostgreSQL "most_specific_type_mismatch" error (2200G) occurs when UNION, CASE, INTERSECT, or EXCEPT queries combine columns or expressions with incompatible data types that cannot be implicitly coerced to a common type. Fixing requires explicitly casting mismatched columns to compatible types.

PostgreSQL error 2202H occurs when a TABLESAMPLE clause receives an invalid argument. The sampling percentage must be between 0 and 100, and arguments must be numeric constants that can be evaluated at query planning time.

PostgreSQL error 0LP01 occurs when attempting an invalid GRANT operation, such as granting privileges you don't own or granting a role to itself. Verify ownership of the object, check user privileges, and ensure correct GRANT syntax to resolve this.

PostgreSQL prevents aggregate functions like SUM(), COUNT(), AVG(), or MAX() in WHERE clauses because WHERE filters rows before aggregation occurs. To filter on aggregate results, use the HAVING clause after GROUP BY, or wrap your query in a subquery or CTE to compute aggregates first.

PostgreSQL throws 2200L (not_an_xml_document) when a string is well-formed XML but does not conform to CONTENT restrictions in XMLPARSE or xml operations. This typically happens when you attempt to parse an XML fragment or multiple root elements as a document, or when DOCTYPE declarations or processing instructions violate the expected CONTENT vs DOCUMENT distinction.

The PostgreSQL error 42P08 (ambiguous_parameter) occurs when a prepared statement or parameterized query contains parameter placeholders that the database cannot uniquely resolve. This typically happens when parameter types cannot be determined from context, or when the same parameter is used in contexts with conflicting type requirements.

PostgreSQL "insufficient privilege to bypass row security" error occurs when a user attempts to access or modify rows in a table with Row-Level Security (RLS) policies enabled, but lacks the BYPASSRLS privilege. This is a security feature that enforces data access restrictions. Fix by granting BYPASSRLS attribute to the role or by creating appropriate RLS policies for the user.

This error occurs when you attempt to calculate a power (exponentiation) with mathematically invalid arguments to PostgreSQL functions like POWER() or POW(). Common causes include raising a negative base to a fractional exponent or zero raised to a negative power, which would result in complex numbers or undefined values that PostgreSQL cannot represent.

SQLSTATE 22002 occurs when a NULL value is fetched from the database but no indicator variable was specified to capture its null status. This commonly happens in embedded SQL (ECPG) or applications using cursor variables without proper null handling.

The PostgreSQL error 2201W "Invalid row count in LIMIT clause" occurs when a non-integer, negative, or otherwise invalid value is passed to the LIMIT clause in a SQL query. LIMIT expects a non-negative integer or NULL, and providing strings, floating-point numbers, negative values, or other invalid types triggers this error. Fixing requires ensuring the LIMIT value is properly validated and cast to an integer in your application code.

PostgreSQL raises HV004 when a foreign-data wrapper encounters a data type mismatch between the local foreign table column definition and the remote object's actual data type. This commonly occurs when PostgreSQL foreign table columns are declared with incompatible types or when using FDWs like oracle_fdw where type conversion is not supported. Aligning the column data types between local and remote definitions resolves the error.

This PostgreSQL error occurs when you try to create a unique constraint or primary key on a partitioned table without including all partition key columns. PostgreSQL enforces uniqueness only within each partition, so the constraint must include the partition key columns to ensure proper behavior. The fix requires adding all partition key columns to your constraint definition.

The "must be owner of table" error (PostgreSQL error code 42501) occurs when pg_restore attempts to perform operations on tables owned by a different user. This typically happens when restoring a dump to a different database environment or when the restoring user lacks superuser privileges.

The "trigger cannot change partition destination" error occurs when a BEFORE INSERT trigger modifies the partition key column on a partitioned table. PostgreSQL determines partition assignment before trigger execution, so changing the partition key value creates a conflict. Redesign triggers to avoid modifying partition key columns, or use alternative approaches like staging tables.

PostgreSQL has activated its vacuum failsafe mechanism to prevent transaction ID wraparound. This emergency response occurs when a table's transaction ID age exceeds the safety threshold and autovacuum hasn't kept up with freezing old transactions, risking database shutdown.

This error occurs when PostgreSQL's parser reaches the end of a statement unexpectedly. It typically indicates incomplete SQL syntax, missing parentheses, unclosed quotes, or incorrect parameter placeholders.

PostgreSQL PANIC: could not write to file occurs when the database runs out of disk space or encounters I/O errors while writing critical data. This is a severe issue that stops the server and requires immediate action to resolve.

This SSL error occurs when the hostname in your connection string doesn't match the hostname in the PostgreSQL server's SSL certificate. The mismatch happens when using verify-full SSL mode, which validates both the certificate chain and the hostname.

The 'No SSL connection' error occurs when a PostgreSQL client expects an SSL/TLS encrypted connection but the server either doesn't support SSL, hasn't enabled it, or the connection parameters don't match. This commonly appears when sslmode is set to require or verify-ca but SSL isn't properly configured.

This error occurs when executing a prepared statement with a mismatched number of parameters. The SQL query expects M parameter placeholders (like $1, $2) but your application is providing N values instead. This commonly happens when parameter placeholders are accidentally placed inside string literals or when parameters are missing from the query.

pg_dump fails with a lock timeout when it cannot acquire AccessShareLock on tables because other transactions hold conflicting locks. This typically happens when active DDL operations or long-running transactions block the backup process.

The 0F000 error indicates a general locator exception in PostgreSQL. This SQL standard error typically occurs when working with Large Object (LOB) locators and signals issues with the locator mechanism itself, often related to invalid or improperly managed large object references.

PostgreSQL requires all sub-arrays in a multidimensional array to have the same number of elements. This error occurs when you attempt to create a "ragged" array with inconsistent dimensions, violating PostgreSQL's rectilinear array structure requirement.