I had exact the same error message after migrating the SQL DB from my staging environment. But i solved it by loggin into the postgres user, then make sure the new created user for strapi have proper privileges with the following lines:
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA <schema_name> TO <username>;
GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA <schema_name> TO <username>;
In my instance i only had one schema called “public” and my user was “strapi_develop”. After the user had proper access, the error message was gone and the server started successfully.
Hope it helps someone!