Rails: PG::InsufficientPrivilege: ERROR: permission denied for relation schema_migrations

I had same issue and I solved by adding “Superuser” to the role.

First, list users and their privileges. If you followed above commands, root user does not have “Superuser” Attributes.

postgres=# \du
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 other     | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 root      |                                                            | {}

Next, upgrade root to be a “Superuser”.

postgres=# ALTER USER root WITH SUPERUSER;
ALTER ROLE

Again, list users and their privileges. Now root has “Superuser”.

postgres=# \du
                               List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 other     | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 root      | Superuser                                                  | {}

Hope it helps.