I just upgraded ambari to 2.7.3 on my cluster. The cluster had previously been configured with kerberos, and running correctly. Now whenever I try to modify components I get an "admin session expired" dialog. I enter my admin credentials (kerberos) and get an invalid KDC admin error returned. I verified that the principal I entered has admin rights by logging into kadmin on the command line. The principal I am entering is the one I used when I initially configured the cluster to use kerberos. Why would this not work anymore, and how can I fix it?