I also got the same problem on Raspberry Pi3 with Ubuntu Mate 16.04 as soon as I did the first update. https://ubuntu-mate.community/t/firefox-55-0-2-doesnt-start-crashes-on-ubuntu-mate-raspberrypi-3/14637 has some workarounds, if anybody thinks to look there.
I also got the same problem on Raspberry Pi3 with Ubuntu Mate 16.04 as soon as I did the first update. /ubuntu- mate.community/ t/firefox- 55-0-2- doesnt- start-crashes- on-ubuntu- mate-raspberryp i-3/14637 has some workarounds, if anybody thinks to look there.
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