When I try to export I get the error as seen in the screenshot.
However there is no feature rclt in the font. And when I create one and let Glyphs fill it automatically it stays empty and still won’t let me export.
Do you have a alternate (bracket) layer in the font?
Yes, I had to review all bracket and brace layers. That fixed my issue.
What was wrong? Something that Glyphs should have prevented?
Basically when opening the Glyphs 2 file in Glyphs 3 it rewrote the bracket and brace layers that I had implemented for width only and gave them a weight number of zero. Once I realised that the fix was just typing in the correct numbers.
Only thing Glyphs couldve done wpuldve been having a more descriptive Error message, so I could have found it on my own.
Do you have the original Glyphs 2 file? It should convert those numbers correctly.