MongoDB Errors

The "socket hang up" error in MongoDB occurs when a network connection between the MongoDB client and server is abruptly terminated. This typically happens due to network timeouts, firewall issues, or server-side connection limits. The error indicates that the TCP socket was closed before the request could complete, often during long-running queries or bulk operations.

The StaleShardVersion error (code 63) occurs when MongoDB components have outdated metadata about shard versions in a sharded cluster. This typically happens during chunk migrations, configuration changes, or when clients cache stale routing information. Applications should implement retry logic to handle this transient error.

MongoOperationTimeoutError: Operation timed out is raised when the driver waits longer than the configured server selection, socket, or operation timeout for a Node to respond. It usually means a slow query, a disconnected replica, or a network boundary closing the TCP connection before the request completes.

MongoDB throws QueryExceededMemoryLimitNoDiskUseAllowed when a blocking aggregation stage needs more RAM than the default limit but the query did not ask to spill to disk, so the plan executor aborts with a sort memory error.

The "MissingSchemaError: Schema hasn't been registered for model" error occurs in Mongoose when you try to use a MongoDB model before its schema has been properly defined and registered. This typically happens due to incorrect import/export order, circular dependencies, or attempting to access models before Mongoose connection is established. The error indicates that Mongoose cannot find the schema definition for the model you're trying to use.

The "DivergentArrayError" in MongoDB/Mongoose occurs when you attempt to save a document after loading it with a partial array projection like $elemMatch. This happens because document.save() would overwrite the entire array with only the projected subset, causing data loss. The error is Mongoose's protective mechanism to prevent this unsafe operation. The solution is to use Model.update() or Model.updateOne() instead of save() when modifying arrays that were queried with projections.

The CastError occurs when MongoDB/Mongoose tries to cast a value to ObjectId format but the value is invalid. This commonly happens when querying by _id with a string that's not a valid 24-character hex string, or when route parameters are misinterpreted as ObjectIds.

This Mongoose error occurs when trying to register a model with the same name multiple times. It commonly happens in development environments with hot-reloading, serverless functions, or test suites that re-import model files.

This error occurs when you try to create an index with a name that already exists but specifies different fields or options. MongoDB requires each index name to uniquely identify a specific index definition.

The "unknown operator: $invalidOperator" error in MongoDB occurs when using an unsupported or misspelled query operator in your MongoDB queries. This typically happens due to typos in operator names, using operators from different MongoDB versions, or incorrect operator syntax. The error indicates that MongoDB does not recognize the operator you're trying to use in your query.

The "OutOfDiskSpace: Disk space is critically low" error in MongoDB occurs when the database server runs out of available disk space for data files, journal files, or temporary operations. This critical error prevents MongoDB from writing new data and can cause database operations to fail, potentially leading to data loss or service disruption if not addressed promptly.

The "bad auth : authentication failed" error in MongoDB occurs when the database server rejects client authentication credentials. This typically happens due to incorrect username/password, missing authentication database, or misconfigured user permissions. The error indicates that MongoDB cannot verify the identity of the connecting client against its authentication system.

This error occurs when attempting to perform read operations on a MongoDB secondary replica set member without proper read preference configuration. By default, MongoDB restricts read operations to the primary node to ensure strict consistency.

MongoDB has a 16MB limit for individual BSON documents. This error occurs when trying to insert or update a document that exceeds this size limit. Common causes include storing large binary data, deeply nested objects, or accumulating too much data in arrays.

This error occurs when MongoDB fails to create an index on a collection due to various constraints like duplicate keys, insufficient permissions, memory limits, or index key size violations. Index creation is critical for query performance but can fail on populated collections with existing data issues.

This error occurs when multiple asynchronous save() operations are attempted on the same MongoDB document instance simultaneously. It's a Mongoose-specific concurrency protection mechanism that prevents data corruption from race conditions. The fix involves implementing proper synchronization or using atomic update operators.

This error occurs when you attempt to perform database operations without establishing a connection first. The MongoDB client requires an explicit connection before executing any queries or commands.

The "MongoInvalidArgumentError: Argument must be a valid connection string" error occurs when the MongoDB driver receives an invalid or malformed connection string. This typically happens due to syntax errors, missing required components, or incorrect formatting in the MongoDB URI. The error prevents applications from connecting to MongoDB databases.

Every MongoDB write concern is guarded by a timeout. When a write needs acknowledgements from more than the primary, the driver waits for those replicas but eventually raises "WriteConcernError: waiting for replication timed out" if the replicas cannot confirm the write before the configured wtimeout expires.

This DNS lookup error occurs when your system cannot resolve MongoDB Atlas SRV records, typically due to DNS server limitations or network configuration issues preventing mongodb+srv:// connections.

MongoDB aborts a transaction that runs longer than the server parameter `transactionLifetimeLimitSeconds` (60 seconds by default). This error shows up when a transaction spends too much time inside the session, usually because of large workloads, missing indexes, or waiting on long-running operations.

The "VersionError: No matching document found for id" error in MongoDB occurs when using optimistic concurrency control with document versioning. This typically happens when trying to save a document that has been modified or deleted by another process since it was loaded. The error indicates a version mismatch between the document in memory and the document in the database.

The TransactionTooLarge error in MongoDB occurs when the total size of all operations within a single transaction exceeds the 16MB limit (16,793,600 bytes). This limit applies to the combined size of all documents being inserted, updated, or deleted within a transaction, including their BSON representation overhead. The error prevents transaction execution and requires breaking large operations into smaller batches or optimizing document size.

The "$out must be the last stage in the pipeline" error occurs when you try to use the $out aggregation stage anywhere except as the final stage in a MongoDB aggregation pipeline. The $out stage writes pipeline results to a collection and must be the last operation. This error prevents pipeline execution and requires reordering stages to place $out at the end.

The DocumentNotFoundError occurs when MongoDB cannot find any documents matching your query criteria. This typically happens when querying with incorrect filters, accessing deleted documents, or working with empty collections. Understanding query patterns and validation can help prevent this error.

The MaxTimeMSExpired error occurs when a MongoDB operation exceeds the maximum execution time limit specified by the maxTimeMS parameter. This server-side timeout mechanism prevents long-running queries from consuming excessive database resources and helps maintain overall system performance.

The "connection refused because too many open connections" error occurs when MongoDB or its client drivers cannot establish new connections due to hitting connection limits. This typically happens in high-traffic applications, misconfigured connection pools, or when connections are not properly closed. The error prevents new database operations until connections are freed up.

TransientTransactionError occurs when MongoDB transactions fail due to temporary conditions like network issues, replica set elections, or resource constraints. This error indicates the transaction can be retried safely. Understanding when and how to retry transactions is key to handling this error.

MongoDB prevents creating compound indexes on multiple array fields to avoid exponential index growth. This error occurs when you attempt to insert a document with arrays in multiple fields covered by a compound index.

This Mongoose validation error occurs when attempting to save a document without providing a required email field. The error indicates that your schema defines email as required, but the field is missing or undefined in the data being saved.

MongoDB throws "BadValue: invalid parameter" during global initialization when it cannot parse the requested locale (LANG / LC_*). Setting a generated UTF-8 locale before mongod/mongos starts and ensuring services inherit those values keeps the server from failing with error code 2.

This error occurs when trying to insert or update a document that violates the collection's validation rules. MongoDB rejects the operation to maintain data integrity based on the schema constraints you've defined.

This error occurs when a MongoDB aggregation pipeline stage exceeds the default 100MB memory limit and disk usage is not enabled. Enable allowDiskUse to resolve it.

The "Cannot find module 'mongoose'" error occurs when Node.js cannot locate the mongoose package in your project. This typically happens when mongoose is not installed, was installed in the wrong location, or when the node_modules directory is missing or corrupted. The error prevents your application from importing mongoose for MongoDB operations.

This error occurs when attempting to use a MongoDB ClientSession after it has been explicitly ended or has expired. Sessions must be active to perform database operations within transactions or to maintain operation consistency.

This error occurs when the MongoDB driver's connection monitoring thread cannot maintain a stable connection to the server. The connection is closed before server selection can complete, typically due to network issues, authentication failures, or firewall restrictions.

This error occurs when attempting database operations after the MongoDB client connection has been closed or when the topology (internal connection manager) was terminated. The most common cause is closing the client prematurely or attempting operations on a stale connection.

The CursorNotFound error occurs when MongoDB cannot locate a cursor that your application is trying to access. This typically happens when a cursor times out after 10 minutes of inactivity, when processing large result sets slowly, or in load-balanced sharded cluster configurations. Understanding cursor lifecycle and timeout management is essential for handling large datasets.

MongoDB raises UnknownTransactionCommitResult when a transaction commit operation encounters a network error, server selection error, or write concern timeout, leaving the commit state uncertain. This error label signals that retrying the commit may succeed, as the transaction might have actually committed despite the error.

This MongoDB error occurs when a query or aggregation pipeline attempts to compare a field value to undefined, which is not a valid comparison type. MongoDB cannot directly compare values to undefined because it treats undefined differently from null and missing fields.

This error occurs when you attempt to save a document with fields that are not defined in your Mongoose schema while strict mode is set to "throw". The fix involves either adding missing fields to your schema or adjusting your strict mode configuration.

The E11000 duplicate key error occurs when you try to insert a document with a value that already exists in a unique indexed field. This prevents duplicate emails, usernames, or other unique identifiers from being stored in your MongoDB collection.

This error occurs when your application cannot connect to MongoDB on the default port 27017, typically because the MongoDB service is not running or misconfigured. Fix it by starting the MongoDB service and verifying your connection settings.

This error occurs when your MongoDB client fails to establish a connection within the configured timeout period. It typically happens due to network issues, firewall blocking, misconfigured timeout settings, or unreachable database servers.

This error occurs when your application tries to write to a secondary node instead of the primary in a MongoDB replica set. Write operations are only allowed on the primary node to maintain data consistency.

This error occurs when MongoDB attempts to sort documents without an index and the in-memory sort operation exceeds the configured memory limit (typically 32 MB by default). Solve it by creating indexes, enabling allowDiskUse, or optimizing your queries.

Your application cannot reach the MongoDB Atlas cluster. This is usually caused by IP whitelisting restrictions, authentication issues, DNS problems, or network connectivity issues. Check your IP access list and connection string credentials first.

The MongoDB driver failed to connect to any server within the default 30-second timeout window. This typically indicates network connectivity issues, DNS resolution problems, or server availability issues that prevent the driver from locating and connecting to a MongoDB instance.