PostgreSQL raises this error whenever an external routine (C extension, FDW, or PL handler) signals a problem with a malformed SQLSTATE. The server enforces the SQLSTATE rules documented in the error-code appendix so that clients receive a predictable error protocol.
SQLSTATE 39001 belongs to class 39 (external routine invocation exception) in PostgreSQL's error catalog. The server assigns that code when it calls an external function, extension, or foreign-data wrapper and the routine returns an SQLSTATE that does not follow the required five-character, uppercase alphanumeric format. PostgreSQL refuses to propagate an invalid state because client libraries map SQLSTATEs to well-known exception classes, and the protective check is described in the official error-code appendix.
Inspect the PostgreSQL log or the client stack trace to identify the function or extension that triggered the error. The log entry for 39001 usually includes the shared object or language name that raised it. You can also turn on verbose logging (set log_min_error_statement=error and log_error_verbosity=verbose) or query pg_stat_activity to watch which statement invokes the extension before the failure. Knowing the precise function lets you open the source that issues the invalid SQLSTATE.
External routines in C call ereport() with errcode() (see the C-language function docs). Check the code path that raises the error; it might look like this snippet from the PostgreSQL documentation:
erreport(ERROR,
(errmsg("something bad happened"),
errcode(ERRCODE_FEATURE_NOT_SUPPORTED)));If the code calls PG_SETERRCODE("some string") or a PL/pgSQL block uses RAISE ... USING ERRCODE = '39abc', the string must be exactly five uppercase alphanumeric characters. Any deviation is the cause of 39001.
Switch the routine to one of the macros defined in the errcodes appendix, or supply a valid five-character SQLSTATE string. For instance:
RAISE EXCEPTION 'invalid input' USING ERRCODE = '22000';In C extensions, prefer macros such as ERRCODE_INVALID_PARAMETER_VALUE or a class-39 code like ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION. These macros guarantee Postgres receives a recognized SQLSTATE, and they keep your extensions aligned with the official error catalog.
Once the SQLSTATE code is corrected, rebuild or reinstall the shared object (or redeploy the PL handler) and run the offending query again. A clean CREATE OR REPLACE FUNCTION, ALTER EXTENSION ... UPDATE, or server restart ensures the updated code path executes. Confirm that the same statement now either succeeds or raises a different, intentional SQLSTATE.
SQLSTATE codes comprise a two-digit class plus a three-digit subclass (for example, 39P01). The errcode appendix lists all supported subclasses for class 39 (external routine invocation). Use that list to choose or verify the SQLSTATE you emit; mixing in random strings or lowercase letters makes PostgreSQL raise 39001 as soon as it validates the value. Always rely on errcode() macros or uppercase five-character literals, and only send custom SQLSTATEs after verifying they meet the documented pattern.
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