The Problem
When trying to upload a Work Item Type Definition (WITD) XML file using witadmin.exe the following error message is shown:
TF212018: Work item tracking schema validation error: TF248020: You cannot specify the ‘Reportable’ attribute for filed ‘System.BoardColumnDone’. You can only define the reportable attribute for Integer, Double, String, or DateTime fields. Remove this attribute for the field, or change the field type and try again.
The Cause
You are probably using an incompatible (older) version of witadmin.exe. As a best practice, make sure you are running witadmin.exe in the same version as your TFS.