locator_exception (SQLSTATE 0F000) signals that a large-object locator or cursor reference is invalid or no longer available within the current PostgreSQL session or transaction.
locator_exception (SQLSTATE 0F000) occurs when PostgreSQL cannot resolve a large-object locator or cursor reference, usually because the locator was released, the transaction ended, or the OID is wrong. Re-open the large object inside an active transaction or recreate the locator to fix the error.
locator_exception
locator_exception is raised when PostgreSQL encounters a locator or cursor identifier that it cannot resolve. Large object functions such as lo_open, lo_read, or lo_write receive a handle that is no longer valid.
The error belongs to SQLSTATE class 0F – Locator Exception. It most often appears after committing a transaction, closing a session, or supplying a mistyped OID to a large object function.
Recreate or reopen the large object inside an active transaction. Always wrap lo_open, lo_read, and lo_close in the same BEGIN ‑ COMMIT block. Verify the OID returned by lo_create or lo_import before reusing it.
When using client libraries, keep the connection alive and avoid sharing locator handles across pooled sessions. If the object was deleted, import or create a fresh large object and store the new OID.
Reading a large object after COMMIT throws locator_exception. Solution – reopen the object in a new transaction.
Passing an OID that belongs to a dropped object triggers the error. Solution – query pg_largeobject_metadata to confirm the OID exists.
Using a locator across different sessions in a pool yields the exception. Solution – fetch and open the object per session.
Keep large object work inside explicit transactions. Close locators with lo_close before COMMIT.
Persist only the OID, not the file descriptor, in application code. Reopen with lo_open each time.
Add foreign-key-like constraints or triggers to stop accidental deletion of large objects still in use.
invalid_locator_specification (0F001) – locator not opened correctly. Solution – use lo_open before read.
object_not_in_prerequisite_state (55000) – using object in wrong state. Solution – verify transaction and lock states.
object_in_use (55006) – cannot drop large object currently open. Solution – call lo_close first.
Yes, PostgreSQL reserves SQLSTATE class 0F for large object and locator issues. Regular tables are unaffected.
No. PostgreSQL invalidates file descriptors at COMMIT or ROLLBACK. Reopen the object in the next transaction.
Sharing OIDs between pooled sessions without reopening triggers locator_exception. Always open the object after checking out a connection.
Galaxy’s SQL editor highlights transaction boundaries and offers AI suggestions that wrap lo_* calls in safe BEGIN-COMMIT blocks, reducing invalid locator usage.
.avif)
.avif){kind=logo}
