When opening it states: “The document could not be opened. Problem with file at line 37941” … I also tried Opt-Shift opening, but it also fails.
I’m running Glyphs 3.0.4 (3098) on MacOS Mojave 10.14.6
I had just duplicated a single master, and I suddenly noticed the lowercase ‘a’ somehow had become incompatible (I hadn’t even made any changes to the duplicate). I thought it’d be a bug, so I shut down Glyphs to reopen the file, but it’s now stuck on the error notification.