SQL Server 2008 R2 Reporting Data Source Error

Q : I'm trying to configure a Reporting Data Source for Microsoft SQL Server 2008 R2 Reporting Services (SSRS) in Microsoft SharePoint integrated mode on a SharePoint 2010 farm. But I get the following error in the SharePoint Unified Logging Service (ULS):

The URL '' is invalid. It may refer to a nonexistent file or folder, or refer to a valid file or folder that is not in the current Web.

The URL value in the error message contains the list name and data source name in the format list name/data source name. When this error appears for the file Projects.rsds in the report library DataConnections, the SharePoint Unified Logging Service (ULS) shows the entries below, one after the other. I've bolded the parts that look important:

A: The part that you bolded in Figure 1 above does point to the problem. The class ID that's listed (as CLSID) can be found by searching another server in the SharePoint farm in which the component is installed.

If you're seeing the error on the SSRS server, then check the registry of a Web Front End (WFE). First, navigate to HKEY_CLASSES_ROOTAppID and search for the globally unique identifier (GUID) that's listed in the data; in this case, 93227a84-1e52-47f4-b758-210d37433b7f.

In your case, the COM exception is being thrown by a missing AvePoint component.

Figure 2 shows the registry settings on a WFE that's missing from the SSRS server.

To solve the issue, either install the AvePoint solution that you installed on the WFE (or WFEs) on the SSRS server that's running in SharePoint Integrated Mode, or remove AvePoint. Ideally, contact AvePoint to let them know about this error condition.

This brings up an important troubleshooting technique. When you encounter a SharePoint error in which the UI doesn't give you a clue about what's causing the issue, search SharePoint ULS to locate the error message or something similar to what you see in the UI.

Then, scroll back from there to see whether you can find an exception, typically categorized as Unexpected. This exception will usually give you a clue about what's causing the error and how to resolve it.

You'll find a few posts about a similar error that can occur with a custom list that's backed by a user-created list instance or list definition.

In that case, the issue involves the ColName property that's specified for a custom field. Even for this type of error, the ULS will probably get you a little closer to the cause and resolution of the problem.