Unable to login via Horizon and getting a 500 error when using the CLI

Issue

• Unable to login via Horizon when users were previously able to login and trying to use any CLI would return a HTTP 500 error code.

WARNING: keystoneclient.auth.identity.generic.base Discovering versions from the identity service failed when creating the password plugin. Attempting to determine version from URL.
ERROR: openstack Authentication failure: Internal Server Error (HTTP 500)

• Trying to restart the keystone service will fail and there're no meaningful logs in this situation.