kromo404 Unfortunately, Spine 3.8 is very old and has been known to have a tendency to crash on startup on newer Mac PCs. We cannot do anything about this as it is due to changes Apple has made to the new macOS. However, as far as we have confirmed, it is not completely impossible to run, and sometimes the run is successful. I have not found a perfect rule on how to succeed, but from what I have tried, it tends to crash more easily if you are doing some other operation while Spine is starting. After the startup, the editor is often able to run stable.
I am sorry to have to answer this way, but I hope you understand that in order to comply with the new MacOS specifications, we will also have to release a new version of the editor, and older versions will no longer be compatible. However, older versions tend to run more reliably on Windows, so if you want to use an older editor version, you may want to use a Windows PC.
