If your SSRS report works fine in BIDS and on-premises instances but fails to upload with very unhelpful message:

An error occurred while trying to add the report to Microsoft Dynamics CRM. Try adding the report again. If this problem persists, contact your system administrator.

then do the simple “1-2-3” test:

1. Ensure that your report uses FetchXml DataSource
2. Remove or replace all denied types and members from the report formulas
3. Make sure that your report doesn’t use any of the custom assemblies