EJP

Well I figured out how to change the file associations and that hasn't fixed it either.

> You may have made file associations, e.g. for STL files to open with Cura. I have indeed. How do I undo that? NB operating system has not been updated. EJP

Thanks for your help but I am really expecting an answer from Ultimaker on this. It is certainly not a hardware problem as it has been running for years. The problem was specifically introduced by version 4.9. I don't consider this to be something I should need to Google about, or read Windows- or Unix-related answers about either. The topic is perfectly expressed in the title.

FYI the second folder appears to be here: $USER/Library/Logs/cura/<Cura version>/ However I found both, and removed both, and found no others, and the problem still remains. And the folders did not reappear. So I can't provide logs. EJP

I installed 4.9 only to find it won't run. So I deleted it and reinstalled 4.8, which did run before, but now it won't, because it considers the IOS too old. Evidently Cura 4.9 has left something behind itself such that even if I delete it and install 4.8 or even 4.7 it now claims neither of those is compatible with MacOS 10.11.6 either, when I was running them both on this machine at different times. What would that have been? and how do I fix it? Or is there another cause? Presently I cannot use Cura at all. EJP

Well then your software shouldn't have installed itself self-incompatibly. In any case Cura 4.9 has left something behind itself such that even if I delete it and install 4.8 or even 4.7 it now claims neither of those is compatible with MacOS 10.11.6 either, when I was running them both on this machine at different times. What would that have been? and how do I fix it? EJP