My Jenkins server lives behind a /jenkins context path and reverse proxy through Apache and when the login request finishes it redirects back to an extra /jenkins when it logs in via Kerberos.  This only started after we enabled the kerberos-sso plugin.

Chrome Dev tools login request/response:

1. Request URL:
   https://<host>/jenkins/login?from=%2Fjenkins%2F

2. Request Method:
   GET

3. Status Code:
   302 Found

4. Response Location:
   https://<host>/jenkins/jenkins/

If I then navigate back to the proper location, I've been successfully logged in.