I can authenticate on my drupal as admin (uid = 1) from almost every url. But, after authenticated, I can see the list of roles/permissions on admin/access. If I update something, after 'Save' drupal says Access denied. Then I cannot relogin while the path is still admin/access.
In the log what says is access denied to path/access to Anonymous. Is like the Drupal.
Regards, maykel