AX2012 EP error : DataSource XXXX in DataSet XXXX has an unknown field XXXX

Cause of the issue: Change in table level field elements.(Adding a new field )

Resolution: 
Any change happen at table or dataset level must be reflected to VS EP project. Best way to do is

• Try to refresh caches  in Development workspace go to
• Tools > Caches > Refresh dictionary
• Tools > Caches > Refresh data
• Tools > Caches > Refresh elements
• If it doesn't solve your problem try to close and reopen visual studio after you clear the caches.
• Final try close all window and restart AOS.