I'm not able to replicate the issue on the distro version nor my separate copy of the same version that I run from a folder. see screenshot

What happens in safe mode? Firefox safe mode: Click the menu button, click Help and select Restart with Add-ons Disabled…. Firefox will start up with the Firefox Safe Mode dialog.

Try downloading a separate copy of Firefox and run it from the folder(do not sign into you Firefox account) to see what happens.

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

Hello,

thank you for helping

I've already tried safe mode (called troubleshooting mode in my menu). It soes not improve the problem.

As you suggested I downloaded a fresh firefox 91.0.1 from mozilla.org. Running this one instead of fedora 34 installed one improves the problem. As this install uses the same preference directory, I suppose we can say the issue is likely caused by a 3rd party library not being up to date in fedora...

So I think next step is to report the issue to fedora.

Best regards

We're sorry to hear that Firefox is crashing. In order to assist you better, please follow the steps below to provide us crash IDs to help us learn more about your crash.

The crash report is several pages of data. We need the report numbers to see the whole report.

1. Enter about:crashes in the Firefox address bar and press Enter. A list of Submitted/Unsubmitted Crash Reports will appear, similar to the one shown below.
2. Copy the 5 most recent Submitted Report IDs that start with bp- and then go back to your forum question and paste those IDs into the "Post a Reply" box.

Note: If a recent Report ID does not start with bp- click on it to submit the report.

(Please don't take a screenshot of your crashes, just copy and paste the IDs. The below image is just an example of what your Firefox screen should look like.)

Thank you for your help!

More information and further troubleshooting steps can be found in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

Hello

here are the 5 most recent crashe report numbers: bp-e72f68d9-ffb1-453c-93c3-27bf90210821 bp-6d6ef225-9576-4bc0-933e-041c90210821 bp-c729840a-d295-43ee-a696-aabf90210821 bp-ee05d71c-a653-4c91-9094-42ea10210821 bp-269b5072-67f2-49b1-bdfc-5119d0210820

I've already followed the troubleshooting guide except that I did not perform memtest86 test recently. I'll do it today and let you know the result.

Best regards

Hello

memtest pass has completed without any error. Best.

Hello

The problem is now solved . Fedora applied an update to firefox package and now the issue is solved.

ventrill ~ $ rpm -q firefox firefox-91.0.1-2.fc34.x86_64 ventrill ~ $

Thank you for your help

That's good to hear. Well Done.

Which is why you should also run a copy from a folder and you could have compared the distro with the separate copy. Just an idea...

@ jonzn4SUSE

I agree with you, and I did follow your suggestion. May be my message was not clear enough : "As you suggested I downloaded a fresh firefox 91.0.1 from mozilla.org. Running this one instead of fedora 34 installed one improves the problem. As this install uses the same preference directory, I suppose we can say the issue is likely caused by a 3rd party library not being up to date in fedora..."

I was trying to explain it worked with a copy installed in a separate directory.

Once again I thank all the participants of the thread for having spent some time in helping with this problem.