We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. On the keyboard, press [Windows] The image "Windows key" does not exist. + [R]. This should bring up a Run window that contains a text field.
2. In that text field, type %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID with bp- into the reply window on the forums.

Thanks in advance!

You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

We're sorry to hear that your Firefox seems to be crashing when you open it. Please perform the following steps to give us a crash report ID that helps us find out more about the cause of the crash.

1. On the keyboard, press [Windows] The image "Windows key" does not exist. + [R]. This should bring up a Run window that contains a text field.
2. In that text field, type %APPDATA% and press Enter. An explorer window should open.
3. From that explorer window, double-click on the Mozilla folder, then double-click on Firefox and then on Crash reports. Double-click on submitted.
4. Now, you should see a list of files that contain reports. Go to View > Arrange Icons by > Modified to get the most recent files at the top of the window.
5. Open the most recent 5 files with a text editor and copy the IDs.
6. Paste each ID with bp- into the reply window on the forums.

Thanks in advance! You can find more information and troubleshooting steps in the Troubleshoot Firefox crashes (closing or quitting unexpectedly) article.

I attempted to follow your instruction, but after running %APPDATA% I saw no Mozilla folder. Before posting my question, I tried one more time to reinstall Firefox and it still would not open. Not sure if I inadvertently deleted any crash reports from when it briefly worked.

I am still running the Microsoft Store version of Firefox, in case that means anything.

Another update: I tried the online-install version again and had the same problem, but this time there was a Mozilla folder in %APPDATA%. I clicked through to the crash reports section, however, this time there was no "submitted" folder.

You are now running Firefox from Mozilla right? What security software are you running? Have you tried Windows in Safe Mode and run Mozilla version of Firefox?

You are now running Firefox from Mozilla right? What security software are you running? Have you tried Windows in Safe Mode and run Mozilla version of Firefox?

Booting Windows in Safe Mode and running the Mozilla/online-download version of Firefox worked! It opened right away and ran how it should normally, without internet service of course. I rebooted my computer in normal mode and Firefox opened again, for maybe 10 seconds, and then crashed and will not open again.

What security software are you running?

What security software are you running?

Just the Windows Security program that comes default with Windows 10 and also the Windows Defender Firewall. I've already tried giving Firefox permission to bypass the firewall, but that didn't help.

Try logging into another Windows account and see if you have the same issue.

Try logging into another Windows account and see if you have the same issue.

I tried this and it worked. I ran Firefox for a short time both logged in to my Mozilla account on the browser and logged out. I was able to open and close Firefox several times with no issues.

So your regular account has add-ons I would assume. The 2nd Windows account had none right?

So your regular account has add-ons I would assume. The 2nd Windows account had none right?

Yes, it's a completely fresh Windows account. I made it just for this purpose and I have downloaded nothing. Firefox actually automatically installed when I added the new account so I have downloaded nothing.

I used the same add-on (AdBlocker Ultimate), theme, and settings on Firefox as I did on my other Windows account. So all of my Firefox settings are the same and have still to this point not caused any problems on this 2nd Windows account.

Here's some issue-I find reading the OP. Microsoft isn't FireFox? Did you use this site to get the lastest build of FireFox? https://ftp.mozilla.org/pub/firefox/releases/ "Are you sure you want to start Firefox in safe mode?" would appear for a split second, and then close. That tells me something got corrupted during the install. What version of FireFox did you have before this issue started? It doesn't sounds like this is a FireFox browser program itself. I've used FireFox before 56 til 97.0.2 when the after 56 had issues where I had to redo my setting and since that time I just upgraded FireFox til 97.0.2 without issues including the second Limited User account had no issue opening and running FireFox.

I did not use that website to get the latest version. I am not sure how to use that website.

I agree that I don't think Firefox itself is the problem. I am no computer expert but it seems to me that I may have a program installed on my computer that is conflicting with Firefox or preventing it from opening. I can open Firefox on another Windows account and it runs perfectly fine. I have no other programs active on that Windows account than what is on Windows by default.

If it is another program interfering with Firefox, I am clueless as to how to identify that program.

Boot your system into Safe Mode with Networking and try the Browser to see if it tries to reinstall or opens a site. But if your not getting FireFox from the site I listed which has the latest version of FireFox that is the only way others on here can figure what FireFox Browser your using from Microsoft site. The site I linked is FireFox and if you scroll to the bottom you can see the latest working version and based on the language. So if you can tell us which language version your using I can see which link version you should download and try to see if that works to fix the issue or not.

I uninstalled Firefox and reinstalled it from the website you provided. I scrolled to the bottom and click on: 99.0b5 > win64/ > en-US/ > Firefox Setup 99.0b5.exe

I booted my computer in safe mode with networking, however, when I clicked the option to see available networks, it is blank. Firefox did run in safe mode, though, as it had in safe mode with the version I had installed previously.

John R said

I booted my computer in safe mode with networking, however, when I clicked the option to see available networks, it is blank. Firefox did run in safe mode, though, as it had in safe mode with the version I had installed previously.

This part to me would tell me this isn't a FireFox install but some kinda apps that isn't related to FireFox itself. I could be wrong or mistaken but FireFox should install and have a folder for itself.

I tried the 98.0.1 version and had the same problem. It just flashed a message saying "you are launching and older version of Firefox" for a split second and would not open. Every time I have installed Firefox it has had its own dedicated folder.

Still having this problem if anyone can help.