AttributeError: NoneType object has no attribute
The Python error "AttributeError: 'NoneType' object has no attribute..." probably means that the Gramps program attempted to retrieve an object (such as a person, or family) by using its internal handle, but the database can't find it. Likely, the object is still there, but the internal database references have become corrupted.
To attempt to fix this issue, first, make a Gramps XML backup.
Then, you need to run the following tools from the menu Tools -> Family Tree Repair in the listed order:
If you still get the error after running the repair tools, then you should try creating a new family tree, and importing your backup. If errors still occur, try running the above tools on the re-imported tree.
If you still have issues, you may need to go back to an older backup.