Kerberos Invalid Ticket Errors

An application or device had an unusually high number of the Kerberos 0x21 error, which indicates that the ticket is not yet valid because the timestamp on the Kerberos request differs from the system time on the Key Distribution Center (KDC) by more than five minutes. To avoid this error, make sure that system time between a client and server is synchronized, or start the Time Synchronization service on the device. Troubleshoot these issues with the w32tm.exe utility.