Need to save a card for later?
Create a bookmark folder in your browser of choice (Chrome, Firefox...), and save individual cards in your bookmarks to view here later.
Revit Based HydraCALC (Ribbon/Toolbar/Location)
Description:
Revit could not complete the external command... System.NullReferenceException
Setup has not been run for HydraCALC
Run HydraCALC setup, and select equivalent length again.