While processing a TGS request for the target server krbtgt XXXXXXXX
did not have a suitable key for generating a Kerberos ticket (the missing key has an ID of 8).
The requested etypes were 18. The accounts available etypes were 23 -133 -128 3 1.
Event Type: Error
Event Source: KDC
Event Category: None
Event ID: 27
The cause of the event is that the client requests a service ticket with a etype 18 (aes256-cts-hmac-sha1-96), which is not supported by Windows Server 2003 but supported by Windows Server 2008 R2. If the Kerberos authentication works properly, you can safely ignore the events. It just informs the clients what etypes it supports.
For more information, please refer to the following articles:
The security principals and the services that use only DES encryption for Kerberos authentication are incompatible with the default settings on a computer that is running Windows 7 or Windows Server 2008 R2
Event ID 27 — KDC Encryption Type Configuration