Data import/export framework (AX 2012 R3) - Assembly error [Solved]

Problem :

When open "Data Import \ Export parameters" or any other setup of data import export framework in Ax dynamics 2012 R3 screen system raises the following errors:

Assembly containing type Microsoft.Dynamics.AX.DMF.ServiceProxy.DmfEntityProxy is not referenced
object CLR object could not be created

error in DIEF

Solution :

1. Navigate to XppIL folder.My case i navigated to:
   C:\Program Files\Microsoft Dynamics AX\60\Server\axtestserver\bin\XppIL.
2. Take a backup of all the files in XppIL folder. 
3. Delete everything inside this folder (Make sure you stopped your AOS service )
4. Restart the AOS service.

You can now move ahead with setting up Data import/export framework parameters.