The return types for the following stored procedures could not be detected

Question

While drag-drop a stored procedure in dbml file I get this error:

Unknown Return Type
The return types for the following stored

Answer 1

I had this error too and finally I found out that I have changed a table field name and in procedure it did not change it yet, and so it showed an error when adding to dbml.
Now you can check this on your procedure and your table that fields are the same.

I hope this experience is useful.