Certain Firefox problems can be solved by performing a Clean reinstall. (XPCOM problems require a reinstall) This means you remove Firefox program files (not any bookmarks etc. in your profile folder) and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

How do I get to www. Mozilla.org without a working browser?

You can use another device to download the setup file to a USB drive.

Thank you so much!! I uninstalled two Firefox folders I had in Program Files, and the new download and installation stilll remembered my tabs I used last.

I had the same problem . My IE still worked so I Googled XPCOM. Good thing I did not buy the registry cleaning software offered. Then I found our about this forum.

I got into

C:\Program Files\Mozilla Maintenance Service and did clicked on UNINSTALL then downloaded a new Firefox with my IE . It worked and I was pleasantly surprised when all my favorites and bookmarks were still there ..I was expecting to loose them .. Good luck!

Thank you! I believe that is the solution I eventually found, and, like you, was very pleasantly surprised to find all my settings intact. Thanks again, Kth

For windows xp sp3, I downloaded and installed firefox setup 26.0.exe on top of the existing firefox after the firefox setup stub 26.0.exe update had been installed. This removed the error "cannot find XPCOM" when using the firefox icon on my desktop.

mein fire fox mozilla startet nich und schreibt Fehlermeldung XPCOM muss fehlt . seit mehrere Wochen versuche es zu instalieren es gelinkt mir nicht ich brauche eure Hilfe Danke voraus baiza

Hi baiza

Try to boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as to see if that helps.

Are you able to delete the Firefox program folder?

ich kann ales andere vom meinem Laptop löschen , nur mozilla kann ich nicht löschen um neue zu instalieren ich kann es nicht starten ,weil es schreibt immer XPCOM probleme ich brauche Hilfe danke baiza

The same problem. In may case it was enough to rename the file dependentlibs.list.moz-upgrade to the file dependentlibs.list in the "Mozilla Firefox" folder.