Comment 132 for bug 1711337

Lars, I went to sites like Gmail or Youtube that I thought had a chance of using optional NaCl, but I haven't been able to reproduce those error messages. I don't think Firefox supports NaCl, even with a plugin. Is it possible you imported browser settings from Chromium and it happened to include their NaCl extension? You could rule this out by moving or deleting ~/.mozilla/firefox then trying again.

herrtimson, an illegal instruction would indicate your system lacks NEON or ARMv7 altogether, the same reason Firefox does not run on ARMv6 boards like Raspberry Pi B+ or Pi Zero. To check, cat /proc/cpuinfo

There's also a chance that ungültiger maschienenbefehl means bad interpreter or not in executable format / File format not recognized. You can troubleshoot this with the ldd and file commands. Compare properties of /usr/lib/firefox/firefox to any working command under /usr/bin

> Oh, and how do I revert this to the ubuntu one? *_*

sudo apt-get purge firefox
sudo apt-get install firefox