Login redirects to api/v1/instance after update to 15.8

Our authentication and authorization is in handled with a Shibboleth IDP and after updating to 15.8.0 on our test instance after login we are redirected to gitlab.hostname/api/v1/instance which results in a 404. If I delete the “api/v1/instance” from the URL then the home page loads as expected. I’ve looked through the configuration and can’t see where this “api/v1/instance” is being specified.

Any ideas where this would be coming from?

I am getting this same issue for my admin account and my personal one, the two I have login info for.

GitLab 15.0.2
GitLab Shell 14.3.0
GitLab Workhorsev 15.0.2
GitLab API v4
GitLab KAS 15.0.0
Ruby 2.7.5p203
PostgreSQL 12.10
Redis 6.2.6

Turns out the problem was with my browser, wiping cookies and stored data allowed me to login again. I wasn’t able to figure out what exactly was the problem as clearing cookies for GitLab and the IDP didn’t help but starting with a fresh browser profile did.

Do you still see the issue in a private browsing session?