I’m getting this error everytime I try to get anything from Revit - it wasn’t happening before. Any ideas?
You are trying to get a type parameter. To do that you must first extract the family type by instance:

Hello Everyone,
Just wanted to say that I managed to solve that by creating a new family type and setting up some HxD paramenters myself - the one being loaded in the project from a generic rectangular beam was not working properly.
After that, everything ran really smoothly and the script it 100% operational 
Thanks everyone!
