Every cause of 42501 on Supabase

42501 means "insufficient privilege". Match your message to a row.

Cause	Typical message	Fix
Missing table privileges	`permission denied for table your_table`	Grant the role the privilege it needs. The tool on this page writes it.
Forbidden schema	42501 on a request that reaches into `auth` or `vault`	API roles cannot access these schemas by design. Supabase mentions a security definer function as the way around it.
Custom schema	42501 on a table in a schema you created	Give the Data API permission to query the schema. Supabase's custom schemas guide has the grants.
Column-level restrictions	42501 on a query that touches a restricted column, including `select *`	Select only permitted columns, or grant the column.
Row level security on write	42501 with a row-level security message on `insert` or `update`	Add or correct the policy. This is a policy problem, not a grant problem.
Sequence privileges	`permission denied for sequence your_table_id_seq`	Grant usage on the sequence.

Rows 1 to 5 are from Supabase's "Database API 42501 errors" page (marked updated 2026-11-03, read 2026-11-10). Row 6 comes from the PostgreSQL manual and our own test against Postgres. Clients often report 42501 as HTTP 401 or 403.

Find 42501 errors in your logs

Supabase suggests this query in the SQL Editor:

select
  timestamp,
  event_message,
  log_attributes['parsed.error_severity'] as error_severity,
  log_attributes['parsed.user_name'] as user_name,
  log_attributes['parsed.query'] as query,
  log_attributes['parsed.detail'] as detail,
  log_attributes['parsed.hint'] as hint
from logs
where
  source = 'postgres_logs'
  and log_attributes['parsed.error_severity'] in ('ERROR', 'FATAL', 'PANIC')
  and log_attributes['parsed.sql_state_code'] = '42501'
order by timestamp desc
limit 100;

Write the fix for your tables

One table is free. The whole schema with a rollback file is $9 one-time, free during launch.

Paste schema SQL or table names

Waiting for a paste.

Who can reach each table

Your tables show up here, one row each, with a choice of who can reach them.

Start clean: revoke older grants from anon and authenticated first, as the Supabase guide does.

The SQL appears here as soon as a table is found.

Parsed in your browser. Your SQL is never uploaded, and no site or database is scanned.

Questions

Which cause is the common one since late 2026?

For a table you just created, the missing table grant. New tables in public no longer receive grants automatically.

Sources

Supabase knowledge base: Database API 42501 errors (marked updated 2026-11-03), read 2026-11-10
Supabase docs: Using Custom Schemas, read 2026-11-10
PostgreSQL manual: Sequence Manipulation Functions, read 2026-11-10
Supabase changelog: Breaking Change: Tables not exposed to Data and GraphQL API automatically (published 2026-04-28), read 2026-11-10