PostgreSQL error 0F001 invalid_locator_specification means the session tried to use an invalid or closed large-object descriptor.
PostgreSQL Error 0F001 – invalid_locator_specification – appears when a large-object function receives a descriptor that is closed, out of scope, or never opened. Reopen the large object inside an active transaction and pass the valid descriptor to resolve the issue.
PostgreSQL Error 0F001
The SQLSTATE 0F001 signals that PostgreSQL received a locator (large-object descriptor) that is not valid in the current context. The database cannot locate the referenced large object because the descriptor is zero, negative, or already closed.
Large-object descriptors are only valid inside the transaction that opened them.
Once the transaction ends or the descriptor is manually closed, PostgreSQL flags any further use as an invalid locator specification error.
The error surfaces during lo_read, lo_write, lo_lseek, lo_close, or any other pg_largeobject function if the supplied descriptor is invalid. It is common in functions, PL/pgSQL code, and client libraries that cache descriptors across transactions.
Unresolved, the error halts data ingestion, file uploads, or blob processing workflows.
Repeated failures can lock users out of binary assets and cause application downtime.
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Yes. Locator errors only apply to PostgreSQL’s large-object API, not to regular BYTEA columns.
No. Descriptors are session-specific integers. Persist the object OID instead and reopen it when needed.
Frequently. Each statement runs in its own transaction, so descriptors expire right after lo_open unless BEGIN is issued.
Galaxy highlights transaction scope in its SQL editor and warns if a lo_open call is outside an explicit BEGIN…COMMIT, preventing the error before execution.
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