After configuring a SQL Server Reporting Services (SSRS) instance for the Kerberos authentication I was not able to connect any more. In particular, I was prompted for the credentials over and over again when trying to access SSRS with a browser. Typically, this is an indication that the Kerberos authentication is not working properly.
In the Security Event log I found a corresponding entry. The value of its property TargetInfo looked like a Service Principal Name (SPN):
TargetInfo HTTP/computername.domainnamecomputername.domainname is the fully qualified name of the server on which SSRS run. But wait, it doesn’t contain the port number!
And according to the document Register a Service Principal Name (SPN) for a Report Server I had to create the SPN with the port number:
Setspn -s http/computername.domainname:port domain-user-accountSo it was not unreasonable to assume that the failed authentication was caused by this SPN mismatch.
Indeed, the problem was fixed by replacing the old SPN with a new one which doesn’t contain the port number:
Setspn -s http/computername.domainname domain-user-account