I have encountered this error with a BCS application that I built and was working for some time.
The Exception / error is
"The closed type does not have a corresponding <PropertyName> settable property"
The BCS application was working inside a farm connection to a list in another network and anther farm for sure.
The List column names were changed ( at least one of them ) and that did break the proxy that was compiled for that BCS model to work with
How to detect such problem :
Browse to the service wcf interface that should show the fields ( you will need to see the source of the page to see the field name from the atom feed)
match those to your Model mapped name ( that is normally dynamically configured by VS )
see the mismatched fields, fix your code and rebuild and redeploy
( and call the list owner let them know of the change and don’t get angry )
Lesson Learned : Cannot depend on uncontrolled lists as solid schemas.
I think the main problem is that the feed sends the Fields display name and not the Internal Name of the list which is unique and static
Microsoft Please have a fix (or guidance)
Best of luck