I stumbled upon this error when i tried importing a 3dm file into Revit after RiR add-in is installed.
To replicate this behaviour. Import attached 3dm (or any 3dm file). It will work.
Install/enable RiR addin. Import attached 3dm (or any 3dm file). Error occurs.
See screenshots for details.
I am assuming Rhino Inside Revit plugin seems to cause an issue/conflict with the built-in “Import CAD” command in Revit.
I’m aware of this problem and still have not a good solution for it.
I’ve implemented a new sample called Sample8 that I hope helps you to work around it meanwhile.
You can pick category using the categories combo box (red arrow).
It imports geometry from a 3dm file to a Revit model or family.
The good thing is that you have the source code in the repository to change it as you want, or request here if you need another kind of import, for instance, import objects separately or taking into account its layer, materials, UserText…