SSRS Error – An error occurred during local report processing

The following error message has occasionally been reported by SSRS users who are trying to generate the report.

An error occurred during local report processing. 
An error has occurred during report processing. 
Cannot create a connection to data source 'xyz'.

You have specified integrated security or credentials in the connection string for the data source, but the data source is configured to use a different credential type. To use the values in the connection string, you must configure the unattended report processing account for the report server.

The error message makes the issue quite clear. It claims that the SSRS service is unable to connect to the data source.

The common reasons and the solution could be –

• The data source wasn’t configured properly after uploading the RDL file. 
• The data source credentials are incorrect. Open the embedded or shared data sources and reconfigure them with the right credentials.
• If you are using a DNS alias as the server name in the connection string rather than the actual machine name.

Hope this solves the problem. If not, drop a message.