The revert shows two versions, both of which are hosed.
The file opened fine originally. When I tried not to save, I got that error message and I now get that error when I try to open the file (and Rhino crashes).
I’m on the road but I backed up right before I left. I pray the file is there on the backup and functioning when get back. Most likely no disaster.
As I said, I have seen this error message before but I was always able to open the file afterwards with no problem.
The Mac file system is great until it isn’t.
It’s ALWAYS smart to have a Time Machine backup setup for just such situations.
I’m not aware of anything else that is reliable.