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 need to do a clean reinstall and remove the Firefox program folder to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

Both programs were deleted with Revo Uninstaller , and fresh install and will work for 3-4 days and error pop up will come back ? Both programs were deleted more than 3 times all ready ?

What programs are you using for protection? Can you tell them to leave the browser alone?

Hello bote110,

Would you please take a look at this article :

https://www.repairwin.com/firefox-xpcom-error-couldnt-load-xpcom/

I'm asking because in your system details I see some extensions that might be malware - but maybe I'm just overly suspicious .....

AVG and Firefox has been running for a couple of years now on my Windows Pro 10 . This just started 3 weeks ago .

bote110 said

AVG and Firefox has been running for a couple of years now on my Windows Pro 10 . This just started 3 weeks ago .

That doesn't mean malware can't sneak in .....

Would you please check your extensions : Options => Add-ons => Extensions, just in case ?

It will only take a few seconds.

Hi, since yesterday I have the similar problem. When I want to launch Firefox it says "couldn't launch the xpcom". Moreover I can't even uninstall my Firefox from pc (the uninstall program just won't launch. Do you have any solution to this kind of problem? I am using W10

Thank you very much in advance

arsielas Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86) Note: Check Both Folders

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

It's still have the same problem ,some one ask about extensions : AVG Online Security {was just installed after this error started} Capture & Print ColorfulTabs Print Edit WE Yahoo Homepage Yahoo Toolbar and New Tab Beside the AVG all the extensions were on for a couple of years now I had installed version 75.0 a couple of weeks ago and just today the error came back All plugins are disable . And the funny thing too is Google Chrome will not load during this time too when I click on it too?

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

Check all of your programs that use the new.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia