I have the same issue, and here’s my case:

• I’m using Okta as the Identity Provider, and I have two clients for two different applications.
  • Users of Type A can log in to Application A with clientA, but not to Application B, and vice versa.

I’ve encountered the error different_user_authenticated in two scenarios:

1. Scenario 1:

   • A Type A user logs into Application A (using Okta account 1).
   • Then they create a new user through the app — this triggers a registration flow that sends an Okta activation link for the new account (account 2).
   • When the user clicks the activation link, they are now logged in as account 2 in Okta.
   • If they return to Application A and try to log in again, they get the error:

     “You are already authenticated as a different user <user> in this session. Please sign out first.”

2. Scenario 2:

   • A Type A user logs into Application A (using Okta account 1).
   • Then they go to Application B and try to log in.
   • After entering the credentials in Okta’s login form, they get the same error:

     “You are already authenticated as a different user <user> in this session. Please sign out first.”

Question:
Is there any way to override or replace the previous user login session in Keycloak instead of showing this error?