GET STACKED DIAGNOSTICS is placed in the main executable section of a PL/pgSQL block instead of in an EXCEPTION WHEN handler GET STACKED DIAGNOSTICS is nested inside a different exception handler where the exception context is not available The command is used in a stored procedure outside of any exception handling structure

Is the "0Z002" error serious?

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

How to fix 0Z002: stacked_diagnostics_accessed_without_active_handler in PostgreSQL

PostgreSQLINTERMEDIATEMEDIUMUpdated Dec 29, 2025· 134 views

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.

Quick fix

Fixes 0Z002

BEGIN
  -- Your code that might raise an exception
  SELECT 1 / 0;  -- This will raise an exception
EXCEPTION WHEN OTHERS THEN
  GET STACKED DIAGNOSTICS
    v_state = RETURNED_SQLSTATE,
    v_msg = MESSAGE_TEXT;
  -- Now you can use these variables
END;

Move GET STACKED DIAGNOSTICS into an EXCEPTION WHEN block
Identify available diagnostic items
Use GET DIAGNOSTICS for non-exception information
Test your exception handler

postgresql — error

$BEGIN
  -- Your code that might raise an exception
  SELECT 1 / 0;  -- This will raise an exception
EXCEPTION WHEN OTHERS THEN
  GET STACKED DIAGNOSTICS
    v_state = RETURNED_SQLSTATE,
    v_msg = MESSAGE_TEXT;
  -- Now you can use these variables
END;
0Z002: stacked_diagnostics_accessed_without_active_handler

What this error means

PostgreSQL's GET STACKED DIAGNOSTICS is a PL/pgSQL command designed specifically to retrieve detailed information about exceptions that have been raised. It works by accessing the exception context stack, which only exists when an exception is actively being handled within an EXCEPTION WHEN block. When you try to call GET STACKED DIAGNOSTICS outside of an exception handler—either in normal code flow or in other blocks—PostgreSQL raises error 0Z002 because there is no active exception context to access.

Typical symptoms

Your PL/pgSQL function fails with error code 0Z002
Error message mentions 'stacked_diagnostics_accessed_without_active_handler'
Functions using GET STACKED DIAGNOSTICS outside EXCEPTION blocks fail
The error occurs at runtime when the function is executed

Common causes

GET STACKED DIAGNOSTICS is placed in the main executable section of a PL/pgSQL block instead of in an EXCEPTION WHEN handler
GET STACKED DIAGNOSTICS is nested inside a different exception handler where the exception context is not available
The command is used in a stored procedure outside of any exception handling structure
Confusion between GET DIAGNOSTICS (for non-exception information) and GET STACKED DIAGNOSTICS (for exception information)

How to fix "0Z002: stacked_diagnostics_accessed_without_active_handler"

1Move GET STACKED DIAGNOSTICS into an EXCEPTION WHEN block

Ensure GET STACKED DIAGNOSTICS is only called within an EXCEPTION WHEN clause. Here's the correct structure:

sql

BEGIN
  -- Your code that might raise an exception
  SELECT 1 / 0;  -- This will raise an exception
EXCEPTION WHEN OTHERS THEN
  GET STACKED DIAGNOSTICS
    v_state = RETURNED_SQLSTATE,
    v_msg = MESSAGE_TEXT;
  -- Now you can use these variables
END;

The GET STACKED DIAGNOSTICS statement must be inside the EXCEPTION WHEN block to access the exception context.

2Identify available diagnostic items

When inside an exception handler, you can retrieve different types of diagnostic information:

sql

EXCEPTION WHEN OTHERS THEN
  GET STACKED DIAGNOSTICS
    v_sqlstate = RETURNED_SQLSTATE,    -- The error code (e.g., '23505')
    v_message = MESSAGE_TEXT,           -- The error message
    v_detail = PG_EXCEPTION_DETAIL,    -- Additional error details
    v_hint = PG_EXCEPTION_HINT,        -- Suggested fix
    v_context = PG_EXCEPTION_CONTEXT,  -- Stack trace
    v_table = TABLE_NAME,              -- Affected table (constraint errors)
    v_column = COLUMN_NAME;            -- Affected column (constraint errors)
END;

Select only the diagnostic items you need. If not set by the exception, they return empty strings.

3Use GET DIAGNOSTICS for non-exception information

If you need diagnostic information outside an exception handler (like row counts after INSERT/UPDATE), use GET DIAGNOSTICS without the STACKED keyword:

sql

BEGIN
  INSERT INTO users (name) VALUES ('Alice');
  GET DIAGNOSTICS v_row_count = ROW_COUNT;
  RAISE NOTICE 'Inserted % rows', v_row_count;
EXCEPTION WHEN OTHERS THEN
  -- For exception info, use GET STACKED DIAGNOSTICS here
END;

GET DIAGNOSTICS works in the main code flow, while GET STACKED DIAGNOSTICS only works in exception handlers.

4Test your exception handler

Create a test case that actually raises an exception to verify your handler works:

sql

DO $$
DECLARE
  v_msg TEXT;
BEGIN
  -- Intentionally cause a division by zero
  PERFORM 1 / 0;
EXCEPTION WHEN OTHERS THEN
  GET STACKED DIAGNOSTICS v_msg = MESSAGE_TEXT;
  RAISE NOTICE 'Caught error: %', v_msg;
END;
$$;

Run this in psql or your database tool to confirm the GET STACKED DIAGNOSTICS call works correctly within the exception handler.

Advanced notes

The difference between GET DIAGNOSTICS and GET STACKED DIAGNOSTICS is important: GET DIAGNOSTICS returns information about the last non-exception statement (like number of rows affected), while GET STACKED DIAGNOSTICS retrieves information about the current exception being handled. GET STACKED DIAGNOSTICS is SQL standard compliant and was introduced in PostgreSQL 9.2 as a replacement for special variables like SQLSTATE and SQLERRM, though those variables still work. When using GET STACKED DIAGNOSTICS with constraint violations, you can access constraint-specific fields like TABLE_NAME, COLUMN_NAME, and CONSTRAINT_NAME. Note that accessing exception blocks has performance overhead due to savepoint creation, so avoid wrapping code in exception handlers unless necessary.

Frequently asked questions

What does "0Z002" mean?: PostgreSQL's GET STACKED DIAGNOSTICS is a PL/pgSQL command designed specifically to retrieve detailed information about exceptions that have been raised. It works by accessing the exception context stack, which only exists when an exception is actively being handled within an EXCEPTION WHEN block. When you try to call GET STACKED DIAGNOSTICS outside of an exception handler—either in normal code flow or in other blocks—PostgreSQL raises error 0Z002 because there is no active exception context to access.
How do I fix "0Z002"?: 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.
What causes "0Z002"?: GET STACKED DIAGNOSTICS is placed in the main executable section of a PL/pgSQL block instead of in an EXCEPTION WHEN handler GET STACKED DIAGNOSTICS is nested inside a different exception handler where the exception context is not available The command is used in a stored procedure outside of any exception handling structure
Is the "0Z002" error serious?: It is a medium-severity error — more of a blocker than a risk. The steps above resolve it.

Official resources & further reading

📚PostgreSQL Official Documentation