Windows 10 will not launch Firefox under any circumstances
Ever since a random point in the middle of the afternoon today, Windows 10 has become completely incapable of running firefox.exe. I have done a complete reinstall multiple times, wiping any and all traces of Mozilla from my system before running the installer again. I have run antivirus scans, and attempted to start Firefox with my antivirus (Avast!) completely disabled. I even tried starting firefox.exe from the command line, using tab completion to ensure that the file existed. No matter what I do, I get an error message from Windows claiming that it can't find firefox.exe, even when this is the result of double-clicking that exact file. This does not happen for any other software, including the portable version of Firefox (which is useless, since nothing is saved and I need my addons). I'm beginning to think that this is the result of either an absurd mistake or deliberate action from Microsoft, as there has been more than one Windows update within the day, and I have noticed other weird issues like my desktop background occasionally just being removed from existence for no reason.
Chosen solution
If you get a "Windows cannot find.." alert then this is a problem with Avast making changes to some registry keys.
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options => Debugger
See also: /questions/1290490 Windows Cannot Find Firefox.exe
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hello,
Try these free programs to scan for existing malware, which work with your existing antivirus software:
- Microsoft Safety Scanner
- MalwareBytes' Anti-Malware
- Anti-Rootkit Utility - TDSSKiller
- AdwCleaner (for more info, see this alternate AdwCleaner download page)
- Hitman Pro
- ESET Online Scanner
Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.
then, if your laptop in clean try a clean re-install :
Note: You might want to print these steps or view them in another browser.
Download the latest Desktop version of Firefox from https://www.mozilla.org/en-US/firefox/all/ and save the setup file to your computer.
After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
Delete the Firefox installation folder, if exist, which is located in one of these locations, by default:
Windows:
- C:\Program Files\Mozilla Firefox
- C:\Program Files (x86)\Mozilla Firefox
Now, go ahead and reinstall Firefox: Double-click the downloaded installation file and go through the steps of the installation wizard. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
Thank you.
Chosen Solution
If you get a "Windows cannot find.." alert then this is a problem with Avast making changes to some registry keys.
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options => Debugger
See also: /questions/1290490 Windows Cannot Find Firefox.exe
I marked the registry tweak as the solution to this, as it is the only possible explanation for the issue. Despite this, I don't officially know if that was what caused the issue, since Firefox has started working again without any reasonable ties to my actions.
I was running the antivirus scans from the first response one-by-one; I know it's just a copy-pasted garbage answer that doesn't apply to my situation, but I wanted to be sure that none of them would change anything before claiming that they didn't. I attempted to launch Firefox each time that the strictest scan provided by one of the antiviruses finished, but nothing changed. The last scan had just finished with no hits when I saw the response about the registry. I immediately opened regedit and navigated to the provided path, only to find nothing related to Firefox, Mozilla, or "Debugger". I then tried to launch Firefox one last time, and it worked. The only virus scan that I ran between when the issue was still present and when it resolved itself returned no results, so it probably didn't cause this.
My hypothesis is that the entity that caused the issue (be it Microsoft, Avast!, or someone else) realized what had happened as a result and tried to patch the issue as quietly as possible by pushing a silent update that nuked the problematic registry entries. This is supported by the fact that the only identical issue to this one that I've found on the Internet was discovered on the same day as my issue, but fixed sooner (before the silent patch).
Modified by Phyremaster