Improper use of GET DIAGNOSTICS or GET STACKED DIAGNOSTICS statements in PL/pgSQL Attempting to access diagnostic information outside of proper exception handling context Malformed exception handling blocks in stored procedures or functions

Is the "0Z000" error serious?

It is a medium-severity error — more of a blocker than a risk. The steps above resolve it.

How to fix 0Z000: diagnostics_exception in PostgreSQL

PostgreSQLADVANCEDMEDIUMUpdated Dec 18, 2025· 119 views

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.

Quick fix

Fixes 0Z000

-- Check function definition
SELECT pg_get_functiondef('your_function_name'::regproc);

-- Or view all functions in your schema
SELECT
    n.nspname as schema,
    p.proname as function,
    pg_get_functiondef(p.oid) as definition
FROM pg_proc p
JOIN pg_namespace n ON p.pronamespace = n.oid
WHERE n.nspname = 'your_schema'
ORDER BY p.proname;

Review your PL/pgSQL function code
Verify exception handler structure
Check PostgreSQL server logs for additional context
Test with simplified exception handling

postgresql — error

$-- Check function definition
SELECT pg_get_functiondef('your_function_name'::regproc);
-- Or view all functions in your schema
SELECT
    n.nspname as schema,
    p.proname as function,
    pg_get_functiondef(p.oid) as definition
FROM pg_proc p
JOIN pg_namespace n ON p.pronamespace = n.oid
WHERE n.nspname = 'your_schema'
ORDER BY p.proname;
0Z000: diagnostics_exception

What this error means

The 0Z000 error code belongs to PostgreSQL's Class 0Z (Diagnostics Exception). In PostgreSQL's error code system, the first two characters denote the error class, while the last three characters indicate a specific condition. The "000" suffix represents the standard or generic error code for that class when no more specific code applies. Class 0Z handles exceptions related to diagnostic operations in PostgreSQL. While 0Z000 is the general diagnostics exception, the class also includes more specific error codes like 0Z002 (STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER), which occurs when attempting to access stacked diagnostics outside of an exception handler. This error is relatively uncommon in typical PostgreSQL usage and usually indicates problems with exception handling logic in PL/pgSQL functions or procedures, particularly when working with GET DIAGNOSTICS or GET STACKED DIAGNOSTICS statements.

Typical symptoms

PL/pgSQL function fails with 0Z000 error code
Exception handling in stored procedures throws diagnostics-related errors
Error occurs during database function execution
Application logs show Class 0Z error codes from PostgreSQL

Common causes

Improper use of GET DIAGNOSTICS or GET STACKED DIAGNOSTICS statements in PL/pgSQL
Attempting to access diagnostic information outside of proper exception handling context
Malformed exception handling blocks in stored procedures or functions
Issues with PL/pgSQL exception propagation or error context
Database internal error related to diagnostic subsystem (rare)

How to fix "0Z000: diagnostics_exception"

1Review your PL/pgSQL function code

Check any functions or procedures that are failing for proper exception handling structure. Look for GET DIAGNOSTICS or GET STACKED DIAGNOSTICS usage:

sql

-- Check function definition
SELECT pg_get_functiondef('your_function_name'::regproc);

-- Or view all functions in your schema
SELECT
    n.nspname as schema,
    p.proname as function,
    pg_get_functiondef(p.oid) as definition
FROM pg_proc p
JOIN pg_namespace n ON p.pronamespace = n.oid
WHERE n.nspname = 'your_schema'
ORDER BY p.proname;

Look for any diagnostic statements that might be used incorrectly.

2Verify exception handler structure

Ensure GET STACKED DIAGNOSTICS is only used within EXCEPTION blocks. The correct structure should look like this:

sql

CREATE OR REPLACE FUNCTION example_function()
RETURNS void AS $$
BEGIN
    -- Your main logic here
    -- ...

EXCEPTION
    WHEN OTHERS THEN
        -- GET STACKED DIAGNOSTICS must be here, not elsewhere
        DECLARE
            v_sqlstate TEXT;
            v_message TEXT;
            v_context TEXT;
        BEGIN
            GET STACKED DIAGNOSTICS
                v_sqlstate = RETURNED_SQLSTATE,
                v_message = MESSAGE_TEXT,
                v_context = PG_EXCEPTION_CONTEXT;

            RAISE NOTICE 'Error: % %', v_sqlstate, v_message;
        END;
END;
$$ LANGUAGE plpgsql;

GET STACKED DIAGNOSTICS used outside of an EXCEPTION block will cause error 0Z002.

3Check PostgreSQL server logs for additional context

Review your PostgreSQL logs to get more detailed information about when and where the error occurs:

bash

# On Linux systems, typically:
sudo tail -f /var/log/postgresql/postgresql-*.log

# Or check log location from psql:
psql -c "SHOW log_directory;"
psql -c "SHOW log_filename;"

Look for the full error message and stack trace, which will help identify the specific function or operation causing the issue.

4Test with simplified exception handling

Create a minimal test case to isolate the problem:

sql

-- Test basic exception handling
DO $$
BEGIN
    -- Force an error
    PERFORM 1/0;
EXCEPTION
    WHEN division_by_zero THEN
        RAISE NOTICE 'Caught division by zero';
END $$;

-- Test GET DIAGNOSTICS usage
DO $$
DECLARE
    v_count INTEGER;
BEGIN
    INSERT INTO test_table (id) VALUES (1);
    GET DIAGNOSTICS v_count = ROW_COUNT;
    RAISE NOTICE 'Inserted % rows', v_count;
END $$;

If these basic tests work, gradually add complexity to find where the diagnostics exception occurs.

5Update PostgreSQL if running an older version

Check your PostgreSQL version and consider upgrading if you're on an older release:

sql

SELECT version();

Some diagnostics-related bugs have been fixed in newer PostgreSQL versions. Review the release notes for your version at https://www.postgresql.org/docs/release/ to see if known issues match your scenario.

Advanced notes

Understanding PostgreSQL Error Classes:

PostgreSQL uses SQLSTATE codes consisting of five characters. The first two characters identify the error class:
- Class 0Z: Diagnostics Exception
- Class 0Z000: Generic diagnostics exception
- Class 0Z002: STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER

GET DIAGNOSTICS vs GET STACKED DIAGNOSTICS:

- GET DIAGNOSTICS retrieves information about the current statement's execution (like ROW_COUNT) and can be used anywhere
- GET STACKED DIAGNOSTICS retrieves information about the current exception and can ONLY be used within an EXCEPTION handler

Available diagnostic items for GET STACKED DIAGNOSTICS:
- RETURNED_SQLSTATE: The SQLSTATE error code of the exception
- MESSAGE_TEXT: The primary error message
- PG_EXCEPTION_DETAIL: Detail message, if available
- PG_EXCEPTION_HINT: Hint message, if available
- PG_EXCEPTION_CONTEXT: Stack trace of the error

Performance Considerations:

Exception handling in PL/pgSQL has overhead. If you're handling many exceptions in high-throughput scenarios, consider alternative approaches like validating data before operations rather than relying on exception handlers for flow control.

Debugging PL/pgSQL:

Enable verbose logging to debug PL/pgSQL execution:

sql

SET client_min_messages = DEBUG;
SET log_min_messages = DEBUG;

This will show more detailed information about function execution and may reveal the source of diagnostics exceptions.

Frequently asked questions

What does "0Z000" mean?: The 0Z000 error code belongs to PostgreSQL's Class 0Z (Diagnostics Exception). In PostgreSQL's error code system, the first two characters denote the error class, while the last three characters indicate a specific condition. The "000" suffix represents the standard or generic error code for that class when no more specific code applies.
How do I fix "0Z000"?: 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.
What causes "0Z000"?: Improper use of GET DIAGNOSTICS or GET STACKED DIAGNOSTICS statements in PL/pgSQL Attempting to access diagnostic information outside of proper exception handling context Malformed exception handling blocks in stored procedures or functions
Is the "0Z000" error serious?: It is a medium-severity error — more of a blocker than a risk. The steps above resolve it.