G2.3.1 [902] will not open an OTF generated by an earlier version of Glyphs in August, 2015.
::edit:: Tested in series [8xx] builds back to [877] and they all work fine. The problem begins with the [9xx] builds.
I’ve had similar issues, an OTF that can be opened in 895 but not 902.
My OTF has a UPM of 500 – maybe that is what makes the newer Glyphs versions choke?
I’ve also had problems opening otf files that I had generated with 901. didn’t look further into it though…
I just fixed a problem with a font that wasn’t opening. Please send me fonts that do not open for testing.