Unsafe New Enum Value Usage — SQLSTATE 55P04

SQLSTATE 55P04 condition unsafe_new_enum_value_usage class 55 — Object Not In Prerequisite State severity ERROR
Reproduced & verified on PostgreSQL 14.23, 15.18, 16.14, 17.10 and 18.4 — identical message on every version.
Last reviewed 29 May 2025 · Reproduced live with the SQL on this page.

! Symptoms Free

A newly added enum value cannot be used yet in the same transaction.

  • The error is written to the server log and returned to the client carrying SQLSTATE 55P04.
  • Any driver (libpq, JDBC, psycopg, npgsql, pgx) surfaces this code in its error object so you can branch on it programmatically.
  • PL/pgSQL can trap it by name: EXCEPTION WHEN unsafe_new_enum_value_usage THEN.

1 Environment & reproduce Free

Severity: ERROR  |  PostgreSQL versions: 12, 13, 14, 15, 16, 17

Reproduce with the exact statement and read the full message in the server log (raise log_min_messages / set log_min_error_statement for more context).

? Root cause Free

ALTER TYPE ... ADD VALUE has restrictions on using the new value within the same transaction.

3 Recovery & verify Free

Steps to resolve 55P04:

  1. Commit the ADD VALUE transaction before using the new value.
  2. Never add and use an enum value in a single transaction.

Reference: PostgreSQL error codes — Class 55 (Object Not In Prerequisite State).