Lock File Exists — SQLSTATE F0001

SQLSTATE F0001 condition lock_file_exists class F0 — Configuration File Error 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

The server reports SQLSTATE F0001 (lock_file_exists), a condition in the Configuration File Error class.

  • The error is written to the server log and returned to the client carrying SQLSTATE F0001.
  • 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 lock_file_exists 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

F0001 belongs to Class F0 — Configuration File Error. In this class, a configuration file is invalid.

The first two characters (F0) identify the error class, so application code can match the whole class via F0000 when the specific code is not needed.

3 Recovery & verify Free

Fix the syntax in postgresql.conf/pg_hba.conf, then reload (SELECT pg_reload_conf();) or restart; the log names the offending line.

Reference: PostgreSQL error codes — Class F0 (Configuration File Error).