insufficient_privilege permission denied for sequence … — 42501

Symptoms

A role tried to read or advance a sequence (often implicitly via a serial/bigserial column or nextval()) without USAGE or UPDATE on that sequence. PostgreSQL reports SQLSTATE 42501.

• INSERTs into a table with a serial column fail even though the role can INSERT.
• Calling nextval()/setval() is rejected.
• The sequence privilege is separate from the table privilege.

What the server log shows

ERROR:  permission denied for sequence orders_id_seq

Why PostgreSQL raises this — what the manual says

the GRANT reference (Notes):

“In the SQL standard, sequences only have a USAGE privilege, which controls the use of the NEXT VALUE FOR expression, which is equivalent to the function nextval in PostgreSQL.”

A serial default calls nextval() on an owned sequence. The role doing the INSERT needs USAGE (or UPDATE) on that sequence in addition to INSERT on the table; otherwise the default expression fails with 42501.

Common causes

• Granting table privileges but forgetting the backing sequence.
• A new role that lacks sequence access in the schema.
• Restoring data where sequence grants were not reproduced.

How to fix it

1. Grant the sequence: GRANT USAGE ON SEQUENCE orders_id_seq TO app_user;.
2. Grant all sequences in a schema at once: GRANT USAGE ON ALL SEQUENCES IN SCHEMA app TO app_user;.
3. Add default privileges for future sequences: ALTER DEFAULT PRIVILEGES IN SCHEMA app GRANT USAGE ON SEQUENCES TO app_user;.

Diagnostic query

-- List sequences and whether the role can use them
SELECT c.relname,
       has_sequence_privilege('app_user', c.oid, 'USAGE') AS can_use
FROM pg_class c WHERE c.relkind = 'S';

Related & next steps

• SQLSTATE 42501 — Insufficient Privilege (full reference)
• Message: permission denied for table …
• Glossary: Sequence

Reference: PostgreSQL 18 — GRANT.