$ firefox -safe-mode
ExceptionHandler::GenerateDump cloned child 3792
ExceptionHandler::SendContinueSignalToChild sent continue signal to child
ExceptionHandler::WaitForContinueSignal waiting for continue signal...

 $ firefox -g
GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2
....
[New Thread 0x7fffe52e3700 (LWP 3166)]
[New Thread 0x7fffe52a2700 (LWP 3167)]
--Type <RET> for more, q to quit, c to continue without paging--

Thread 1 "firefox" received signal SIGSEGV, Segmentation fault.
0x00007ffff2719c5b in ?? () from /usr/lib/firefox/libxul.so

This is a question I am migrating from LQ - the original question (with a bunch of details) is here: https://www.linuxquestions.org/questions/linux-software-2/firefox-won%27t-start-on-xubuntu-4175691712/ The issue is that Firefox will not start on my Ubuntu 20.04. This started randomly a few weeks ago - it might be related to an update, but I did not noticed anything specific. Here's the error messages: $ firefox -safe-mode ExceptionHandler::GenerateDump cloned child 3792 ExceptionHandler::SendContinueSignalToChild sent continue signal to child ExceptionHandler::WaitForContinueSignal waiting for continue signal... As detailed in that post, I have tried many variations of reinstalling, scrubbing my system, making sure I am updated, and looking at the systemd logs. Since then, I have also tried to run firefox with gdb, and I get a seg fault: $ firefox -g GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2 .... [New Thread 0x7fffe52e3700 (LWP 3166)] [New Thread 0x7fffe52a2700 (LWP 3167)] --Type <RET> for more, q to quit, c to continue without paging-- Thread 1 "firefox" received signal SIGSEGV, Segmentation fault. 0x00007ffff2719c5b in ?? () from /usr/lib/firefox/libxul.so I have found some suggestions that errors relating to libxul may be memory related, but I passed a memtest86 this morning, so back to zero. Anyone here have any thoughts?