The error message below will appear in the system log:
"The Kerberos client received a KRB_AP_ERR_MODIFIED error from the server "server name". The target name used was HTTP/server_name.domain.local. This indicates that the server failed to decrypt the ticket provided by the client. This can occur when the target server principal name (SPN) is registered on an account other than the account the target server is using. Ensure that the target SPN is only registered on the account used by the server. This error can also happen if the target service account password is different than what is configured on the Kerberos Key Distribution Center for that target service. Ensure that the service on the server and the KDC are both configured to use the same password. If the server name is not fully qualified, and the target domain "domain.local" is different from the client domain "domain.local" check if there are identically named server accounts in these two domains, or use the fully-qualified name to identify the server."
The solution is quite simple but perhaps not obvious even though it's stated in the error message. What you need to do is to add two SPN's to your CAU account.
- Open an elevated command prompt
- setspn -S http/CAU-account-name CAU-account-name
- setspn -S http/CAU-fqdn-account-name CAU-account-name