An exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll but was not handled in user code

Additional information: Unable to process the type 'Whatever[]', because it has no known mapping to the value layer.

If you are popping an IQueryable off to a List and then trying to use that List as an assignment at another IQueryable it just won't work. You'll end up with this error. Instead, you should get that second IQueryable off to a List and then do the doctor up. There was time when I was child when I got kicked out of a waterslide park in my hometown of West Palm Beach, Florida for doing things I wasn't supposed to do like standing up on the mat like I was surfing or trying to stop on the slide and let others crash into me. IQueryable is kinda like a waterslide in that there is a lot of stuff you just can't do on slides. String.IsNullOrWhiteSpace will also not work, etc.