We’ve been getting a few phone calls where Revit users have been receiving this error when opening a file:
This issue usually occurs when upgrading models. What I have done to help resolve this error is clean up the model in the version it was created in. Remove all non-essential links and imported CAD files. Update any linked models and especially any custom families to the newest version.
If this does not work then you’ll need to submit a case directly with Autodesk to see if they can help:
directly with Autodesk to see if they can help: Submitting &Viewing Support Requests