0F000ERRORTier 3 — Handle with care✅ HIGH confidence

locator exception

Category: Locator ExceptionVersions: All Postgres versions

What this means

SQLSTATE 0F000 is the generic locator exception code. In the SQL standard, locators refer to large object references (LOBs). Postgres raises this when an operation on a large object locator is invalid.

Why it happens

1Invalid operation on a PostgreSQL large object (lo_open, lo_read, lo_write, lo_close) using a stale or invalid OID

How to reproduce

Operating on a large object with an invalid descriptor.

trigger — this will ERROR

SELECT lo_read(99999, 1024); -- invalid file descriptor

ERROR: locator exception

Fix 1: Use valid large object OIDs and descriptors

When working with PostgreSQL large objects (pg_largeobject).

fix

-- Create a large object first, then use the returned OID:
SELECT lo_create(0); -- returns OID
-- Then open with lo_open() using that OID

Why this works

Ensure the large object OID exists in pg_largeobject before opening, and use the descriptor returned by lo_open() for subsequent operations.

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 for large object operations. Stable across versions.