FATAL Error while generating OpenType Font in Fontlab

Ryan Fruest10 August 2011 · 15:100 votes

Everything was going fine with my font until today when I generated my font and I got this error message:

[FATAL] GPOS feature 'kern' causes overflow of offset to a subtable (0x11420)
ERROR: There was a problem while compiling OpenType font. Final .otf font is not saved. Please, check OpenType features definition for errors
[FATAL] GPOS feature 'kern' causes overflow of offset to a subtable (0x11420)
ERROR: There was a problem while compiling OpenType font. Final .otf font is not saved. Please, check OpenType features definition for errors

I have over 6,000 kerning pairs in the font so far. I'm wondering if I reached the limit and that's why it's doing this?

Thanks in advance to anyone that can help.

Ryan Fruest10 August 2011 · 16:190 votes

Nevermind, I figured out how to fix it.

I compressed the kerning and apparently it converted about 1500 pairs into classed-based kerning, so the number of pairs I had went from over 6000 to 4800. This got rid of the FATAL error. I also noticed through experimentation that the error didn't appear until I had over 6000 pairs, because I started working on a previous one with about 5900 that was fine. When it went to about 6,005 I tried generating the font, and boom, there was the error.

6000 is the limit aparently.