I have a dead profile because of this bug. Other profiles work fine, my main one won't start any content processes anymore. The browser chrome and at least some chrome-privileged about: pages work (about:crashes, about:addons, about:support), but all I have is the main Firefox process and the Socket process. No child processes. In case it's a clue this seems to have started when my webextension process seemed to be "stuck" (high CPU, pages were frozen) so I killed it. After that browser is non-functional, even after restarting and updating.
A high number of today's crashes are from me. It seems to send off many crash reports every time I restart. More than I have windows (4), but fewer than I have tabs open (150-ish?). There are 10 new crashes each restart (one for each child process that didn't start?), but only 4 get submitted. The others show up in "unsubmitted" and fail when I try to manually submit them. Are these failures logged anywhere, and would that log be useful?
Anything you want me to preserve for investigation? Otherwise I think it's new-profile time.