Undocumented error when trying to add a dataset to an RDLC report

I have the same problem. It is not as perfectly clear as the earlier responder thinks. All I have to do is click 'New --> Dataset' in the report designer and the 'Undocumented Error' popup is displayed. In the details, it says 'Could not load file or assembly ' and then it names one of the referenced projects in the solution.

This happens at design time, not run time. There is no code involved.

My workaround is to design (or modify) my reports in a separate project with no references to other projects in the solution, and then copy the report to the intended project.

What do you mean "undocumented"? The error is perfectly clear. You are trying to use an object that is null. Debug your code, find the object that is null, fix your code so that the object is not null.

:thumbsup:

:)