P0001ERRORTier 2 — Caution✅ HIGH confidence

raise_exception

Category: PL/pgSQL ErrorVersions: All PostgreSQL versions with PL/pgSQL

What this means

A PL/pgSQL function executed a RAISE EXCEPTION statement. This is the standard mechanism for signalling application-level errors from stored procedures and functions.

Why it happens

1PL/pgSQL RAISE EXCEPTION reached in a function or procedure
2Business rule validation failed and the function deliberately raised an exception
3Trigger function rejected an operation via RAISE EXCEPTION

How to reproduce

Any PL/pgSQL function, procedure, or trigger that calls RAISE EXCEPTION

trigger — this will ERROR

CREATE OR REPLACE FUNCTION check_age(age int) RETURNS void AS $
BEGIN
  IF age < 18 THEN
    RAISE EXCEPTION 'Age must be 18 or older, got: %', age;
  END IF;
END;
$ LANGUAGE plpgsql;

SELECT check_age(15);

ERROR: P0001: Age must be 18 or older, got: 15

Fix 1: Satisfy the business rule that triggered the exception

Input data failed a validation check

fix

SELECT check_age(21);  -- provide valid input

Why this works

Pass data that satisfies the condition checked in the PL/pgSQL function

Fix 2: Catch the exception in the calling code

The exception is expected for some inputs

fix

BEGIN;
  BEGIN
    PERFORM check_age(15);
  EXCEPTION WHEN raise_exception THEN
    RAISE NOTICE 'Caught expected error: %', SQLERRM;
  END;
COMMIT;

Why this works

Handle P0001 in an EXCEPTION block to implement graceful fallback

What not to do

✗

Do not swallow P0001 exceptions silently without logging

Why it's wrong: Business rule violations are important signals; silent catch-and-ignore hides bugs

Sources

📚 Official docs: https://www.postgresql.org/docs/current/plpgsql-errors-and-messages.html

🔧 Source ref: https://www.postgresql.org/docs/current/errcodes-appendix.html

📖 Further reading:

Confidence assessment

✅ HIGH confidence

The most common PL/pgSQL error SQLSTATE; well-documented standard behaviour.