If you are facing issues backing up your PostgreSQL database, ensure that your database user has enough permissions to actually back up the database.
You may use the following queries to grant read access on your target database:
GRANT CONNECT ON DATABASE "your_databbase_name" to postgres_user;
GRANT SELECT ON ALL TABLES IN SCHEMA your_schema_name TO postgres_user;
GRANT SELECT ON ALL SEQUENCES IN SCHEMA your_schema_name TO postgres_user;