Yesterday, I saved a file with 5 masters, 21 instances and 2 axes, then quit Glyphs. When I reopened it, I got a message saying the file couldn’t be reopened. I assumed the file was corrupted. My last backup file was four days old.
Inexplicably, the corrupt Glyphs file would open just fine in FontLab VI. I ended up exporting UFO files from FontLab VI, then opening them in Glyphs. I had to recombine all the individual files into a new Glyphs file. Using my four-day-old backup, I recreated a few missing custom parameters, set up all the master and instances information, then corrected the path direction for all the masters.
Various other things, like glyph outlines themselves, kerning pairs, etc., seem to be OK. The file exports to OTF just fine and all seems to be good.
Never having had a need to do this before and no advice on what I was doing, I can’t help but think I’ve missed something important. Are their any gotchas I’ve overlooked that I probably ought to check?