Hi noremacniai, as you can imagine, this is not because of a recent update on Firefox's side, and probably it's not something Apple issued either, although you would know better than I. So it could be an add-on or website is triggering the crash, or some other software added to or updated on your system.

If you are getting the Mozilla Crash Reporter form, your Firefox may have logged some data that would help track down the cause of the problem. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the support article "Firefox crashes - asking for support" for steps to get those crash report IDs from the about:crashes page, and then post some of the recent ones here.

(You might have copy/pasted from one of those, but the online interface is much easier to use.)

Also and/or meanwhile, could you test in Firefox's Safe Mode? That temporarily deactivates extensions, hardware acceleration, and some other advanced features of Firefox that might make it more prone to crashing on some systems.

If Firefox is not running: Hold down the option/alt key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any less crashy?

Hi jscher2000, Many thanks for your time/effort/feedback. You're right about it having nothing to do with updates - Either Firefox or Apple or anything - It just started out of a clear blue sky - This is the crash report - https://crash-stats.mozilla.com/report/index/bp-205c99e7-463f-4da1-9c88-8d0640181121

I'll try Safe Mode but it doesn't happen with enough frequency to be sure.

Many thanks, noremacniai