When integrating single sign-on for Domino you may see a variety of errors that tend to be rather generic. In most cases, when you see a red toast message that appears related to credentials, we recommend logging out completely then logging back in to trigger a new token to be issued.
If the issue is not fixed after initiating a fresh session, we'll want to dig deeper into the root cause.
This specific error:
User could not be (de)activated: Access token for current user not found
was triggered by the user having empty "first name" and "last name" fields within Keycloak.
We'll add more cases as they come up to assist in troubleshooting.
As always, if you need further help, please reach out to Domino support.