Fix Firefox Couldn’t Load XPCOM error message on start

Firefox is one of the commonly known and popular web browsers after Google Chrome. Mozilla releases its web browser updates regularly and sometimes after the upgrade it also becomes incompatible with the operating systems. This is mainly due to its newly added features or due to some pre-installed programs.

The most irritating message that appears in such a situation is “Couldn’t load XPCOM

You might have tried to fix this error by running various virus scans, removing junk files by clearing cache and also performing a system reboot. But you may have noticed that none of these attempts is helpful while fixing the error.

Also Check: How to Fix Widevine Content Decryption Module Update Error?

In this article, I will provide you with the causes and solutions of this error and I will provide you with some effective methods that will prove very helpful to solve this error.

Every operating system may use a separate solution to the problem I have tried my best to list them here.

Causes Of FireFox XPCOM Error

The XPCOM error may occur due to the following reasons:

  • There are chances that you may encounter this error in Windows OS based computer. It usually occurs when a user updates the Windows and then opens Mozilla Firefox frequently.
  • This error also occurs if the Firefox’s profile folder id corrupted l. Firefox’s profile folder corruption usually occurs due to a virus attack or after installing a third-party extension on the Firefox browser.

How to Fix Couldn’t Load XPCOM Error

Now let’s discuss the methods to fix “Couldn’t Load XPCOM Error“.

1. Fix Couldn’t Load XPCOM error in ThinderBird

Thunderbird programs and ThunderBird profile folders are not stored in the same place. So you can uninstall Thunderbird and then reinstall a new and updated version without any adverse effects on emails and downloads etc.

To uninstall the program follow the steps below:

Step – 1: Go to Start and then select Settings.

Step – 2: Now go to the control panel and select ‘Programs and Features’.

Step – 3: Now select Mozilla Thunderbird and then click on the uninstall button.

2. Fix Couldn’t Load XPCOM Error in Tor Bundle Browser

If the XPCOM error appears when you open the Tor Browser Bundle, that is because Webroot security software was preventing Tor from irritating.

Though you don’t have to delete your webroot security software package. Just follow these simple steps below:

Step – 1: Open Webroot and then click on Identity Protection.

Step – 2: Find that file which contains the word ‘tor’ in c:\users\desktop\torbrowser\browser’

Step – 3: Now on the right side you will find the following options: protect, allow, deny

Step – 4: Select ‘allow’ from these options.

Now this will fix the XPCOM problem in Tor Bundle Browsers.

3. Fix Couldn’t Load XPCOM Error In Windows

Run an Anti-virus through the system

The precautionary measure to ensure before resolving the XPCOM Firefox problem is to make sure that if your computer is free of malware or viruses.

First of all, Boot your computer into Safe Mode

For Windows 7, Vista and XP

Step – 1: Restart your computer and press the F8 key before the Windows logo appear

Step – 2: The advanced options menu appears on the screen to SafeMode with networking option and then press enter.

For Windows 10, 8.1 and 8

Step – 1: Press Windows + R keys to open the RUN window.

Step – 2: Now type misconfig and select OK.

Step – 3: Go to the Boot tab

Step – 4: Now choose the Safe Boot and Network Options and then select OK.

Step – 5: Now restart your computer.

Run TDSSKiller Anti-rootkit utility

Step – 1: Download Kaspersky’s TDDSSKiller Anti-rootkit utility in your computer.

Step – 2: Run TDDSS Killer

Step – 3: Accept the License agreement

Step – 4: Now tap on Next.

Step – 5: Use the Smart Scan button and wait until the scan is finished.

Step – 6: Now select the “Cure” to remove the errors (if found).

Delete malicious entries from Windows Startup

Step – 1: First of all, download and Install CCleaner

Step – 2: Run CCleaner utility

Step – 3: Now select Tools

Step – 4: Tap on the Startup button

Step – 5: Choose the Windows tab

Step – 6: Select and delete any suspicious entry that is listed there.

Uninstall Unknown or Unwanted programs

Step – 1: Open Windows Control Panel.

Step – 2: From the programs list find and remove any unknown or unwanted application that is listed here.

Reset your Firefox Browser Settings

This step is optional you can apply it if you want to. If the XPCOM error still occurs then make sure that all the useless plugins, extensions, and settings were removed from the browser when the above steps were performed.

Just follow the steps given below:

Step – 1: From Mozilla Firefox’s menu icon choose Help.

Step – 2: Select troubleshooting information.

Step – 3: Now click the Refresh Firefox button.

Step – 4: Select Reset Firefox again

Step – 5: Close all open Firefox windows.

If the XPCOM error persists imply of any methods enlisted below for an error-ridden Firefox browsing experience.

Also Check: Best Chrome Cleanup Tool for Windows, MAC & Android

Step-by-Step Guide

Try reinstalling and Upgrading Firefox to the latest version

Run the Firefox installer and follow the on-screen instructions to repair and upgrade the current Firefox application. You can get the latest version of firefox from the internet.

Uninstall Firefox completely and then re-install it

If the above option didn’t prove beneficial for you then try following this one.

Complete uninstall means that you need to remove everything related to Firefox from your computer like:

  • Uninstall Firefox
  • Remove Registry Entries
  • Remove from program files
  • Delete Entries from AppData folder
  • Delete entries from the Program Data folder

It is recommended that tempering with the registry editor because the wrong registry keys may lead to other complications.

Also Check:


Q1. What causes the XPCOM error?

The XPCOM error may be caused on a Windows-based computer whenever a user tries to open Mozilla Firefox after a Windows update or if Firefox’s profile folder is corrupted.

Q2. What is the file XPCOM?

XPCOM.dll is a type of DLL file associated with Firefox which is developed by Mozilla Foundation of the Windows operating system. The latest known version of XPCOM.dll is 17.0.6, which is produced for Windows. This DLL file carries a popularity rating of 2 stars.

Q3. What do you do when Firefox won’t open?

  • Find the firefox.exe program file in the Firefox application folder on your system.
  • Right-click on the icon.
  • Select Run As Administrator
  • The firefox application is started using the administrator Windows account.

Q4. Will resetting Firefox fix the XPCOM error message?

Yes, resetting Firefox to its default settings can often fix the XPCOM error message, as it clears out any problematic settings or extensions that may be causing the issue.

Q5. Can I prevent the XPCOM error message in Firefox?

You can prevent the XPCOM error message in Firefox by keeping the browser and its plugins up to date, avoiding downloading files from suspicious websites, and using a reputable antivirus program to scan for malware regularly.

Leave a Comment