CRM 2015 - Reports - SPN / SSPI Problems

 Running a report on CRM and if you fin an error message similar to this:

If you see an error like this:

Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: Query execution failed for dataset 'DSMain'. ---> Microsoft.Crm.Reporting.DataExtensionShim.Common.ReportExecutionException:
Microsoft.Crm.CrmException: An unexpected error occurred.
System.ServiceModel.Security.SecurityNegotiationException: A call to SSPI failed, see inner exception.
System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception.
System.ComponentModel.Win32Exception: The target principal name is incorrect ---> 

It means the CRM App Pool service account SPN is not configured properly and usually the fix is the one described below:

On the CRM App Server run the following commands:

setspn  -a  HTTP/[Crm App Server Name]  [Domain]CRMAPP_Account
setspn  -a  HTTP/[Crm App Server FQDN]  [Domain]CRMAPP_Account

The Crm App Server FQDN might be something like CrmAppServerName.domain.com or something slightly different, so you'll need to figure this out for your specific environment. For example, if your server name is CrmAppServer and your domain is FooDomain.local you will have something like the following:

setspn  -a  HTTP/CrmAppServer  FooDomainCRMAPP_Account
setspn  -a  HTTP/CrmAppServer.FooDomain.local  FooDomainCRMAPP_Account

After, if SQL also runs under a domain account we'll need to log onto the SQL server and run the following commands for the SQL account:

setspn  -a  MSSQLSvc/[SQL Server Name]:1433 [Domain]SQL_Account
setspn  -a  MSSQLSvc/[Sql Server FQDN]:1433 [Domain]SQL_Account

Hope it helps.