Every 15 minutes this event logged on my SQL servers:
A Kerberos error message was received:
on logon session
Error Code: 0x7 KDC_ERR_S_PRINCIPAL_UNKNOWN
Extended Error: 0xc0000035 KLIN(0)
Error Data is in record data.
Error 0x0000035 means that we have an issue with duplicate SPNs.
Find duplicate SPNs on the server where the event occure
Run cmd as administrator:
Found 1 group of duplicate SPNs.
Look for duplicate SPNs in the domain
Run cmd as administrator on the domaincontroller.
ldifde -f C:\SPNs.txt -t 3268 -d dc="DOMAIN",dc="COM" -l serviceprincipalname -r (serviceprincipalname=*) -p subtree
Delete duplicate SPN
setspn -D MSSQLSvc/sql1.example.com:1433 sql1