The server returned a non-specific error when trying to get the data view from the data source

Error when creating a SOAP Data Source in SharePoint Designer 

With Microsoft SharePoint Designer 2010, you can easily link data sources that contain interrelated data to one another. You can even link data sources of separate types — for example, you can link an XML file to an SQL database. By linking multiple data sources, you create a single data source that appears in the Data Sources list with all of your other data sources.

Consider the following scenario:

§  You create a web application which is configured to use claims-based authentication with NTLM 

§  You create a custom list or use an existing list with some data. 

§  You create a SOAP data source in SharePoint Designer & configure to authenticate as a claims user 

In this scenario, you receive an error similar to the following

The server returned a non-specific error when trying to get the data view from the data source

Cause: I am trying to find out the root cause behind this issue but most probably the answer would be- SharePoint impersonates the anonymous IIS user account and is denied access to the resource.

Resolution:

1.      Open IIS Manager. 

2.      Expand site and find the application to which you are connecting from SharePoint Designer. 

3.      Right click, select Explore. 

4.      Open the web.config file 

5.      Search for <appSettings> 

6.      Find the line with <add key="aspnet:AllowAnonymousImpersonation" value="true" /> 

7.      Change it to <add key="aspnet:AllowAnonymousImpersonation" value="false" /> 

8.      Save the file 

9.      Add the Data View from SharePoint designer.

If you have any queries/questions regarding the above mentioned information then please let me know, Thank you