0F001ERRORTier 3 — Handle with care✅ HIGH confidence

invalid locator specification

Category: Locator ExceptionVersions: All Postgres versions

What this means

SQLSTATE 0F001 is raised when a large object locator (OID) specified by the client does not refer to an existing large object in pg_largeobject, or when the locator value itself is malformed.

Why it happens

1Passing a non-existent large object OID to lo_open, lo_read, lo_write, or lo_unlink
2Large object was deleted (lo_unlink) while a descriptor to it is still in use

How to reproduce

Opening a large object with an OID that does not exist.

trigger — this will ERROR

SELECT lo_open(0, 262144); -- OID 0 does not exist

ERROR: invalid large-object descriptor

Fix 1: Verify the OID exists before operating on it

Before calling lo_open or related functions.

fix

SELECT loid FROM pg_largeobject WHERE loid = :my_oid LIMIT 1;

Why this works

Check pg_largeobject to confirm the OID exists before opening. If missing, handle the absence gracefully in the application.

Sources

📚 Official docs: https://www.postgresql.org/docs/current/errcodes-appendix.html

🔧 Source ref: Class 0F — Locator Exception

📖 Further reading: Postgres Large Objects

Confidence assessment

✅ HIGH confidence

Standard SQLSTATE subcode for invalid LOB locator. Stable across versions.