Issue: When upgrading families with type catalogs to Revit 2021, "Invalid column unit type: ..." or "Could not parse column header: ..." appear.
In family type catalogs and other database export operations, units and related objects are identified by specially formatted text strings.
Revit 2021 introduces corrections and formatting changes to these database identifiers. Content generated in earlier versions of Revit may need to be updated for compatibility with Revit 2021 if it includes references to certain identifiers. The changes are listed in Units in the Revit 2021 Help.
Solution: Manually edit the type catalogs to incorporate the new unit types.