System.IO.Exception error: “The requested operation cannot be performed on a file with a user-mapped section open.”

Question

I received a very weird IOException when writing to an XML file:

System.IO.IOException: The requested operation cannot be performed on a file with a user-map         


        

Answer 1

Looks like another process had the file open using the file mapping (shared memory) APIs.

The find function in Process Explorer should be able to tell you.