How often have you gone to pull up your internet only to encounter an error? If you’ve run into an error called xpcom.dll, you were likely working in Mozilla Firefox or perhaps Thunderbird and then your program unceremoniously shut down on you. While kicking or punching the computer might be considerably more satisfying in the moment, it would make far better sense to just handle the problem – the DLL for Mozilla isn’t working correctly.

What is XPCOM.dll?

DLL files are the files necessary to make program work. The DLL works behind the scenes to ensure everything is working smoothly, but sometimes the DLL file is corrupted on start-up or has an internal glitch that causes it to stop working correctly. When the DLL file goes bad, the whole program can go bad. You might start seeing error messages or you might find yourself looking at a frozen screen. That’s if you’re able to get Firefox to open at all.

Fortunately, as frustrating as a XPCOM.dll error can be, it has a simple solution – you just need to remove the corrupted file and reload the correct one so that all of your programs can work normally again.

Method 1: Updating Firefox

What Version Do I Have?

Often the DLL errors that occur in Firefox can be resolved by simply updating the software. If you can open Firefox, you can check if you’re using the latest version by clicking on the Firefox button in the top left corner of the screen. From there, click on Help and then About Firefox.

If you’re using the most current version, the screen that pops up will let you know that immediately.



If you have a newer version to update, you’ll find a link to that version and you can take care of the update right then. This might fix the problem for you, and you’ll be up to speed and back in business.

Uninstalling

If you don’t have a new updated version available or updating your version of Firefox didn’t work, you’ll need to take things a step further and actually uninstall the version of Firefox or Thunderbird that you have and then install the program again to give it a fresh start without corrupted components.

Method 2: Removing and Installing Firefox

To remove Firefox or Thunderbird, start by clicking on Start and then Control Panel. In Control Panel, you’ll click on either Add and Remove Programs if you’re using an older version of Windows or Programs and Features in a newer version, Vista or 7.

Inside the menu that opens, you’ll have a list of programs running currently on your machine. Locate the Mozilla Firefox (or Thunderbird) program and highlight it. Then click on Uninstall at the top of the screen to uninstall the program.



You’ll be asked to confirm your choice and you may be presented with an online survey about you removing the program as well. There’s not a penalty for ignoring the survey if it appears, by the way. Once you’ve removed Firefox, you may be asked to restart your system, and be sure to follow the instructions as you go to complete the process.

Next, you’ll need to go back in and reinstall Firefox so that you have a version that is working correctly without the XPCOM.dll error. To do this, you absolutely have to visit the Mozilla website for downloads. Downloading from any other site risks introducing malware to your system since many malware developers like to hide their programs in files named the same as DLL files to avoid easy detection.

Going to the Mozilla page to download Firefox should help you avoid any of these problems, however. To be even safer, do a security sweep of your system before and after you download and install Firefox.

On the Mozilla download page, you’ll see a green button to download a free version of Firefox. Go ahead and start the download by clicking on the button, Get Firefox.



You’ll simply follow the instructions for the install. Once it’s installed completely and you’ve restarted your browser or possibly your computer, your Firefox or Thunderbird should be completely up to date and totally free of errors as well. Now it’s yours to fully enjoy again!

More Mozilla Help

To get info and help with other Firefox issues, see these articles:

• Speed up FireFox
• Fix Copy/Paste Errors in Firefox
• Deal with "Firefox is Already" running error