The data set name is missing in the data region 'DataSetName'

Question

I added an additional, new DataSet to my report and have been getting this cryptic error ever since.

Answer 1

The issue was that when the report had elements setup using the first data set I'd defined when the report was created. Adding an additional data set reset the DataSetName value to be blank. In this case for my Table but it could be for a List, etc.

To correct:

1. Open the report in SQL Server Business Intelligence Development Studio (AKA Visual Studio)
2. View the object details in the Properties Window (View > Properties Window or press F4)
3. Check the DataSetName value (under the Data section)
4. Update the value to point to the correct Data Set

Answer 2

Examine your RDLC file, open it in a XML editor. Most specifically, take a look at the Dataset section. See if there are some old ones that are still there. You can edit this file directly, but be careful what you do.

You can also attempt to run the RDLC file through a XML validator, and see if it comes up with any errors. Make sure to validate against the RDLC file's schema. (http://schemas.microsoft.com/sqlserver/reporting/2005/01/reportdefinition/ReportDefinition.xsd)