SSRS / SSAS: AdomdErrorResponseException user or db connection error

When you get this error when you try to open an SSRS Report from AX that contains SSAS Cubes you should check if there is a security issue.

Microsoft.ReportingServices.ReportProcessing.ReportProcessingException

Microsoft.AnalysisServices.AdomdClient.AdomdErrorResponseException: 
Der Benutzer 'DOMAIN\user123' kann nicht auf die Dynamics AX-Datenbank zugreifen, oder die Datenbank ist nicht vorhanden. 

Either the user, DOMAIN\user123, does not have access to the Dynamics AX database, or the database does not exist.

If the security settings are fine navigate to the SSRS Report manager and check the OLAP Connection string:

1. Open Report Manager. http://[SSRSServerName]:80/Reports
   
2. Click the DynamicsAX folder
   
3. Click the DynamicsAXOLAP data source
   
4. In the Connection string field, check the Database and Initial Catalog
   
5. Change it if neccessary and try again
   
   
   
   Provider=MSOLAP.4;Integrated Security=SSPI;Persist Security Info=True;Data Source=SSASServerName;Initial Catalog=SSASDatabaseName