I can get the browser to start without safe mode by unchecking “Use hardware acceleration when available” in settings > general > performance. However, it is very unstable -- lots of crashing tabs and occasional browser crashes.

You can try to set this pref to true on the about:config page or downgrade to Mesa 21.0.3.

• about:config => gfx.x11-egl.force-disabled = true

See this bug report:

• 1739344 - Linux Mint distro build: about:support crashes (caused by non-default Mesa 21.2.0-devel. Fixed by downgrading to distro Mesa.)

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)

The browser starts up with gfx.x11-egl.force-disabled = true. But I have always been running the distro default Mesa 21.0.3. So the workaround is good, but the cause may be different?

$ glxinfo | grep version server glx version string: 1.4 client glx version string: 1.4 GLX version: 1.4

   Max core profile version: 3.3
   Max compat profile version: 3.3
   Max GLES1 profile version: 1.1
   Max GLES[23] profile version: 3.0

OpenGL core profile version string: 3.3 (Core Profile) Mesa 21.0.3 OpenGL core profile shading language version string: 3.30 OpenGL version string: 3.3 (Compatibility Profile) Mesa 21.0.3 OpenGL shading language version string: 3.30 OpenGL ES profile version string: OpenGL ES 3.0 Mesa 21.0.3 OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

Run this to see what's going on.

strace -t -o firefox_debug.txt firefox &

I ran strace, but tbh I'm not sure what to do with the results. Not sure it's wise to send a syscall trace to the internet at large. Any advice?

$ egrep '(glx|mesa)' firefox_debug.txt 22:16:41 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0", O_RDONLY|O_CLOEXEC) = 3 22:16:41 openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libxcb-glx.so.0", O_RDONLY|O_CLOEXEC) = 3 22:16:41 openat(AT_FDCWD, "/usr/share/drirc.d/00-mesa-defaults.conf", O_RDONLY) = 34 22:16:41 openat(AT_FDCWD, "/usr/share/drirc.d/00-mesa-defaults.conf", O_RDONLY) = 34 22:16:41 openat(AT_FDCWD, "/usr/share/drirc.d/00-mesa-defaults.conf", O_RDONLY) = 34 22:16:41 openat(AT_FDCWD, "/usr/share/drirc.d/00-mesa-defaults.conf", O_RDONLY) = 37 22:16:41 openat(AT_FDCWD, "/usr/share/drirc.d/00-mesa-defaults.conf", O_RDONLY) = 37 22:16:41 stat("/home/nat/.cache/mesa_shader_cache", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0 22:16:41 openat(AT_FDCWD, "/home/nat/.cache/mesa_shader_cache/index", O_RDWR|O_CREAT|O_CLOEXEC, 0644) = 38

$ ls -l /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0 lrwxrwxrwx 1 root root 20 Nov 22 00:23 /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0 -> libGLX_mesa.so.0.0.0

$ ls -l /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0 -rw-r--r-- 1 root root 488216 Nov 22 00:23 /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0

$ ls -l /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 lrwxrwxrwx 1 root root 19 Mar 27 2020 /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 -> libxcb-glx.so.0.0.0

$ ls -l /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0.0.0 -rw-r--r-- 1 root root 112856 Mar 27 2020 /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0.0.0

Don't need the all the info just maybe a few seconds before the crash and a little after. You can paste text here. https://paste.opensuse.org/ and provide the link. Don't forget to change the "Delete After" time at the bottom. Also, I think it's a good idea to run a separate copy of Firefox so that you can compare your distro version against Mozilla. I kept losing tabs with openSUSE version a year ago and Cor-el had me try a version from Mozilla(I picked Nightly) and have been using it as my daily ever since. See screenshot of the versions I run from the Download folder plus the distro version.

Try downloading another copy of Firefox and run it from the folder, no install required. Do not sign into your Firefox account and see if you have the same issue.

https://www.mozilla.org/en-US/firefox/all/#product-desktop-release