User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Safari/604.1.38 Steps to reproduce: In both Firefox Developers Edition 57.0b5 and Firefox 56 (64 bit) on Mac OS X many of my fonts are showing up as Question Marks in boxes. I am running MacOS Sierra 10.12.6 on a 5,1 MacPro with 32GB of RAM. Actual results: This did not happen before I installed these 2 version. Firefox was working just fine. Expected results: Normal fonts should have shown.

The workaround in the forum post at https://bugzilla.mozilla.org/show_bug.cgi?id=1404919#c1 worked for me. I was able to reduce my sandbox to 1 and that got rid of the problem.

Thanks for your confirmation! Marking as a duplicate then.

Jonah, to help us debug this, could you run the following command in the Terminal app (/Applications/Utilities/Terminal) and post the output to this bug or bug 1404919? system_profiler SPFontsDataType|grep Location|awk -F . '{print $NF}'|sort|uniq -c More info on https://bugzilla.mozilla.org/show_bug.cgi?id=1404919#c7 Thanks!