You should try uninstalling the Mozilla firefox and re-install the same. Then, signing in to your account should bring back all the necessary items.

I uninstalled firefox, then reinstalled last night. It did not help. I powered down overnight and logged into my administrator account and it opened. I then logged into another admin account and it did not open (same as reported). Went back to my account and firefox, now, will not open. 0% cpu/1.4MB Memory

This is a possibility; You can check for issues caused by a corrupted or incomplete Visual C++ installation that is missing runtime components (Redistributable Packages) required by Firefox, especially VCRUNTIME140_1.dll.

Install both 32-bit and 64-bit "Visual Studio 2015, 2017 and 2019" downloads, (x86: vc_redist.x86.exe and x64: vc_redist.x64.exe) from https://support.microsoft.com/help/2977003/the-latest-supported-visual-c-downloads

You may not need the latter (32-bit version) if you use 64-bit Firefox. You may have to reboot the computer. ++++++++++++++++++++++++++++++++++++++++++++++ In another thread, a user reported that a recent update of Malwarebytes Anti-Exploit (version 415) may be causing symptoms similar to the VC Runtime problem. If you have MBAE, it should have a setting to exempt Firefox. You could test whether that makes any difference.

Did not solve problem.

Name PID Status User name CPU Memory (active private working set) Architecture Description firefox.exe 1208 Running Tom G 00 1,292 K x64 Firefox firefox.exe 864 Running Tom G 00 1,328 K x64 Firefox firefox.exe 4264 Running Tom G 00 1,292 K x64 Firefox

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Firefox has opened once since the update, so it is likely the firewall is not blocking it. I am not comfortable adjusting the firewall that has been working for 5+ years until the update KB5008353 changed the situation. Has Mozilla been in contact with Microsoft? I have filed a report with MS but have not had a response.

I guess MS is driving the boat and Mozilla must do the bailing when it leaks.

Removed KB5008353. All is well again. Pass this on to Mozilla & Microsoft. Oh I dread the next MS update.

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems. Go to that post and click the 'Solved' button to its right.

I think you need to fill out a bug report. Make sure you include all information they will need to fix the issue.

Read this first: Bug Writing Guidelines{web link}

Then go to: https://bugzilla.mozilla.org/ Be sure to include everything that the people there need to know.

reported

For anyone interested in seeing this bug; https://bugzilla.mozilla.org/show_bug.cgi?id=1752466 firefox not opening since 2022-01 Cumulative Update for Windows 11 for x64-based Systems (KB5008353)

A post was flagged as Solved Problem. If the problem is not solved, please remove that flag. If you don’t, others that can help may not read this post.

Go to that message, and use the Undo link to its right.

The question was did the reply solve your problem? Removing the update resolved it for me. Mozilla or Microsoft have not indicated that they have resolved the incompatibility between the programs. I have also reported the problem to MS tech community. Hopefully they monitor their communities to see these posts.

If you think it should go unsolved let me know.

Tom

Good. You flagged your response as the solution. That is what I wanted.