You may receive this kind of error when querying or mapping fields to Dynamics CRM objects: 

Retrieve can only return columns that are valid for read.  Column : isprivate. Entity : account"

If you receive this error, the field is likely not valid for reading purposes. You can check to see if that field is valid by navigating through Microsoft's Entity Documentation and checking if your object's field has the following field flag: "IsValidForRead": False.