permission denied for pg_temp_XX when vacuuming

[Tobias Lott <tobias.lott@xxxxxxxxxxxx>]

Hi,

I have a database in a PostgreSQL 12 instance.

When running vacuumdb -z on the database with the user set as owner of the DB, I sometimes, not always, get errors such as:

error: vacuuming of table "pg_temp_93.vacuum_l" in database "10050" failed: ERROR: permission denied for schema pg_temp_93

The specific number of the pg_temp schema (pg_temp_XX) is always changing. What could be the reason for this error?

Thanks and best regards,

Tobias