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My computer was recently wiped by accident. During the recovery process, I ran a wide variety of tools to recover my computer, and for the most part, I got my apps and files back. I also used this as an opportunity to clean up my computer--and this is where the problem started.

I am no longer a Firefox user, so I decided to uninstall the Firefox app that my file recovery had so helpfully reinstalled for me. I clicked through Settings->Apps->Installed Apps and uninstalled Firefox. Problem solved.

Except, it's not. Every time I open my computer, a little Firefox error pops up, informing me that Firefox:

Couldn't load XPCOM.

A few Google searches of this error indicate that this is most likely being caused by some lingering executable on my computer that is still futilely trying to open a browser that does not exist. Searches through my computer (I'm using Windows 11, btw) indicate that the computer thinks that Firefox is still installed.

Image showing "Firefox" searched in the start menu, 3 options:

However, the apps menu in settings indicates that Firefox is long gone:

Image showing the apps menu, with apps before and after Firefox in the alphabet, and no Firefox in between them:

I just want the app gone. Can anyone help me with this? Thanks!

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Couldn't load XPCOM

Couldn't load XPCOM

Possible reasons of above error message are:

  • An XPCOM missing error is always a problem with files in the Firefox program folder and is usually caused by security software that is locking files and preventing Firefox from replacing all the files.
  • An error message about XPCOM missing or about the platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder.
  • The XPCOM error is caused on a Windows-based computer whenever a user tries to open Mozilla Firefox after a Windows Update or if the Firefox’s profile folder is corrupted. Firefox’s profile folder corruption may happen after a virus attack or after installing a third-party extension on your Firefox browser.
  • This message indicates failure to load application extension file xpcom.dll.
  • Someone got this error after Firefox notified him to upgrade and he clicked to do so. He used chrome browser to download the newest version of Firefox (22) and it works OK now (all his settings retained). The xpcom.dll is not now in the Mozilla Firefox directory. Maybe it is not used in the latest version.

Note:

You always have to remove the Firefox program folder and possibly disable your security software or boot Windows in Safe Mode to get a clean reinstall. Your steps may have worked if you rebooted a few times in case an update didn't complete properly.

Solutions:

This issue would normally be fixed with a clean reinstall that involved deleting the Firefox program folder.

(64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
(32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

An error message about XPCOM missing or about platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder.

This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files.

You can do a clean reinstall to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

You can find the full version of the current Firefox release (61.0.1) in all languages and all operating systems here:

If you want to solve this error using a video demonstration run your PC in Safe Mode and follow below steps:

Couldn't load XPCOM Firefox - How to Fix Firefox Error

Detailed steps from the video

References:

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Thank you, @SoftSol! I really appreciate this! For the record, what ultimately solved this problem was going to C:\Program Files\Mozilla Firefox and deleting the folder. Mozilla Firefox has now been completely uninstalled.
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If you have this issue now on Windows 10:

  1. restart your computer
  2. try to find file xul.dll.moz-backup,
  3. remove new xul.dll and make copy of xul.dll.moz-backup as xul.dll.

This should fix the problem with launching Firefox.
Then, if successfully restored working, try to complete the update.

My Firefox install was in folder: C:\Users\<user_name>\AppData\Local\Mozilla Firefox\.

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Removing or renaming updater.exe resolves.

https://stackoverflow.com/search?q=couldn%27t+load+%22XPCOM%22

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