The Target Principal Name Is Incorrect. Cannot Generate SSPI Context (SQL or AD Issue)? We had a power outage last night and when the server came back up our domain users could not access our SQL Server 2000 instance name: MASSQL.

We can access using SQL Authentication.


We tried making sure the user that runs the service has SSPI read and Write
We tried creating a new user
We tried running the service using NETWORK SERVICE account
We tried running as Local System Account
We tried creating a new Domain Admin account and run service as the new Domain Admin account


I also ran the following command against the problem SQL Server instance:

setspn -L xsql2


Results

Registered ServicePrincipalNames for CN=MASSQL,CN=Computers,DC=ABC,DC=com:
        HOST/MASSQL
        HOST/MASSQL.ABC.COM

I ran the following command against a non-problem SQL instance:

setspn -L xensql1


Results

Registered ServicePrincipalNames for CN=XENSQL1,CN=Computers,DC=ABC,DC=com:
        WSMAN/XENSQL1
        WSMAN/XENSQL1.ABC.com
        RestrictedKrbHost/XENSQL1
        HOST/XENSQL1
        RestrictedKrbHost/XENSQL1.ABC.COM
        HOST/XENSQL1.ABC.COM

It seems the results for the non-problem instance have more data.  I do not know if this has to do with the fact one is 2000 and the other is 2012.

What likely happened?  How do I allow domain users login again?
Use setspn -X to look for duplicate SPNs for the SQL Server in question.  

Remove any duplicate SPNs that don't line up the SQL Server Service account in question.

Service Principal Names for SQL Server take the form of:

MSSQLSvc/server.domain:port
MSSQLSvc/server:port

Assuming your SQL Server is using the default TCP port, 1433, I would expect you need the following servers:

MSSQLSvc/MASSQL.abc.com:1433
MSSQLSvc/MASSQL:1433

You can create those SPNs using the following command:

SETSPN -A MSSQLSvc/MASSQL.abc.com:1433 DOMAIN\Account
SETSPN -A MSSQLSvc/MASSQL:1433 DOMAIN\Account

Where DOMAIN\Account is the name of the service account used by SQL Server.

If your SQL Server uses a named instance, the SETSPN commands look like:

SETSPN -A MSSQLSvc/MASSQL.abc.com:1433 DOMAIN\Account
SETSPN -A MSSQLSvc/MASSQL:1433 DOMAIN\Account
SETSPN -A MSSQLSvc/MASSQL.abc.com:INSTANCENAME DOMAIN\Account
SETSPN -A MSSQLSvc/MASSQL:INSTANCENAME DOMAIN\Account