SQL Server error log entry : Error: 17806, Severity: 20, State: 14
Any time I have seen this error in my environment (0x8009030c and State 14), it has been because the SQL Server engine account was running with a Domain service account, and that account was locked at the time a Kerberos connection was attempted.  The connection would work, but it would be kicked down to NTLM.

Method 1:


Go to register  start –> run … Regedit
Go to:  HKLM\System\CurrentControlSet\Control\LSA
Add a DWORD value called “DisableLoopbackCheck”
Set this value to 1
Rebooted after making this change.


After this registry change was effected.

Method 2. This somehow worked for me: Restarting the sql browser services:

Also, for more info on the related issue, refer to below article:

http://www.allenkinsel.com/archive/2010/06/sql-server-and-sspi-handshake-failed-error-hell/