How to diagnose and fix the 39001 invalid_sqlstate_returned error code in Postgres.

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The 39001 error code in PostgreSQL, which stands for invalid_sqlstate_returned, is typically encountered when a function or trigger programmed in an external language (such as PL/Python, PL/Perl, etc.) returns an invalid SQLSTATE code. SQLSTATE codes are standardized error codes that are used to indicate the success or failure of SQL operations.

To diagnose and fix a 39001 error, consider the following steps:

  1. Review Function or Trigger Code: Check the code of the function or trigger that is returning the error. Look specifically for places where it is returning or raising an exception with a SQLSTATE code.
  2. Ensure Valid SQLSTATE Code: Make sure that any SQLSTATE code returned by the function or trigger is valid according to the SQL standard. A valid SQLSTATE code is a five-character string, with the first two characters being letters and the last three being digits.
  3. Check External Language Handlers: If you’re using an external language to write your functions or triggers, ensure that the language handler is correctly installed and configured to work with SQLSTATE codes.

Here are some examples and sample code to illustrate:

Example 1: Invalid SQLSTATE in PL/pgSQL Function

CREATE OR REPLACE FUNCTION test_sqlstate()
RETURNS void AS $$
BEGIN
    RAISE EXCEPTION 'Error occurred' USING ERRCODE = 'ABCDE'; -- Invalid SQLSTATE
END;
$$ LANGUAGE plpgsql;

This function will raise a 39001 error because 'ABCDE' is not a valid SQLSTATE code. To fix this, change 'ABCDE' to a valid SQLSTATE code, such as 'P0001' for a custom user-defined exception.

Example 2: Invalid SQLSTATE in PL/Python Function

CREATE OR REPLACE FUNCTION test_python_sqlstate()
RETURNS void AS $$
# container: plc_python_shared
raise plpy.Error('Error occurred', 'ABCDE')  # Invalid SQLSTATE
$$ LANGUAGE plpythonu;

Similar to the PL/pgSQL example, this PL/Python function raises a 39001 error because 'ABCDE' is not a valid SQLSTATE code. Correct it by using a valid SQLSTATE code:

CREATE OR REPLACE FUNCTION test_python_sqlstate()
RETURNS void AS $$
# container: plc_python_shared
raise plpy.Error('Error occurred', 'P0001')  # Valid SQLSTATE
$$ LANGUAGE plpythonu;

Example 3: Invalid SQLSTATE in a Trigger

If you have a trigger function that is supposed to return a particular SQLSTATE upon a certain condition but uses an invalid code, it will result in a 39001 error. Ensure that any SQLSTATE codes used in triggers conform to the standard format.

When you encounter a 39001 error, carefully review any custom error handling in your functions or triggers to ensure that all SQLSTATE codes are valid. If you’re unsure about the SQLSTATE codes or how they should be used, refer to the PostgreSQL Documentation for a comprehensive list of standard SQLSTATE codes and their meanings. Additionally, for more context on this error, you can refer to resources like Metis Data, which explains that an invalid SQLSTATE was returned from a PostgreSQL server, likely due to an invalid query or syntax error.

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