Fix Mozilla Firefox Failed to Load XPCOM Error on Windows 10

February 6, 2023

Mozilla Firefox is a reliable web browser that is compatible with most devices. However, from time to time, the error message "Failed to load XPCOM" appears. XPCOM is Mozilla Firefox's cross-platform component model, so the Cannot load XPCOM error breaks browsing. You can click the OK button to close the error message, but you won't be able to use the Firefox application. The article deals with the error and explains the methods to resolve the XPCOM Firefox error.

How to Fix Mozilla Firefox Couldn't Load XPCOM Error on Windows 10

For a list of reasons why an XPCOM error occurs in Firefox, see this topic.

Outdated Firefox. This error may be caused by an outdated version of the Firefox app.
Corrupted Firefox user profile. The user profile in the Firefox web browser may be corrupted or contain malware sources.
Third party extensions in Firefox. The problem with XPCOM can occur if third-party extensions are installed in the Firefox application.
Corrupted system files. System files installed locally on your PC may have been corrupted or your PC may have been infected with a virus.

Method 1: Basic Troubleshooting Methods

The first approach to resolve the "Unable to load XPCOM" error is to try the basic troubleshooting methods listed in this section.

1. Restart your computer

There may be some glitches on your PC that prevent you from using the Firefox browser; you can restart your computer to fix the error. Press the Windows key, click the power button in the lower left corner, and select the Restart option to restart your computer.

2. Check your internet connection

An unstable internet connection may prevent you from using the Firefox browser. You can test your connection speed with the Speed test and evaluate its quality.

If the speed is slow, try using any other Wi-Fi network to browse in Firefox.
Consider changing your Internet connection plan to a better plan.

3. Switch to a different web browser

If the XPCOM error in the Firefox web browser is still not resolved, you can try switching to a different web browser such as Google Chrome. Follow these steps to switch to a different browser:

1. Launch Settings by pressing the Windows + I keys at the same time.

2. Click Application Settings.

3. Click Default Applications in the left pane.

4. Scroll down and click the current web browser.

5. Select one of the options according to your preference.

4. Delete temporary files

Numerous temporary files stored locally on your PC may have disrupted browsing activity in Firefox. You can read how to delete temporary files on your computer using the link provided here.

5. Recover corrupted files

The files on your PC may be corrupted and have some issues that can cause the "Unable to load XPCOM" error. Read the article to repair system files in Windows 10 from corrupted files using the link provided here.

6. Restart Windows

In most cases, using an outdated OS can cause problems on a PC; you need to update Windows on your computer to the latest version in order to fix this error. Read the article on how to update Windows on your PC at the link provided here.

7. Run the Windows Update Troubleshooter.

Issues with the Firefox browser can be fixed using the Windows troubleshooter on your PC. Read the way to run the Windows troubleshooter from the link here and fix the error.

8. Temporarily disable your antivirus (if applicable)

Third party security services on your PC may prevent you from using the Firefox app; you can disable your antivirus program to fix this error. Follow the steps in the link here to disable the antivirus software on your PC.

9. Perform a system restore

If the Firefox app worked better on a previous version of your Windows PC, you can try performing a system restore on your PC to fix the error. The link provided here will provide you with a way to perform a system restore on your PC.

Method 2: Run Firefox as an administrator

The "Failed to load XPCOM" error can appear if Firefox does not have administrator rights on your PC. You must run the Firefox application as an administrator on your PC in order to fix the error.

1. Press the Windows key, type firefox and click "Run as administrator".

Method 3: Refresh Firefox Browser

This error may be caused by using an outdated version of the Firefox web browser. Follow the steps below to update the Firefox app on your PC.

1. Press the Windows key, type Firefox and click Open.

2. Click the "Open application menu" button (denoted by three horizontal lines) in the upper right corner of the home page and select the "Settings" option from the displayed list.

3. On the General tab, click the Check for Updates button in the Firefox Updates section.

4. You will see a Firefox update message in the Firefox Updates section.

Note. If an update is available for the Firefox browser, you will be prompted to do so.

Method 4: Refresh Firefox Browser

To fix the "Unable to load XPCOM" error in the Firefox app, you can completely update Firefox.

1. Launch the Firefox app from the Windows search bar.

2. Then click the "Open application menu" button and select "Help" from the displayed list.

3. Click Troubleshoot Mode... in the Firefox Help window.

4. Now click the Restart button on the Restart Firefox in Troubleshooting Mode popup.

5. Click the "Update Firefox" button in the "Open Firefox in troubleshooting mode" confirmation window.

6. Then click the "Update Firefox" button in the "Update Firefox to Default" window.

7. Finally, click the "Finish" button on the "Import completed" window to fully update Firefox.

Method 5: Disable Firefox Extensions

Extensions in the Firefox web browser can be the cause of the "Failed to load XPCOM" error. You can disable browser extensions to fix the error.

1. Open the Mozilla Firefox application from the Windows search bar.

2. Click the "Open application menu" button and select "Help" from the displayed list.

3. Now click "Troubleshooting Mode..." in the Firefox help window.

4. Click the "Open" button in the "Restart Firefox in Troubleshooting Mode" pop-up window.

5. Then click the "Open application menu" button and select "Add-ons and themes" from the list.

6. Click the "Extensions" tab in the left pane of the next window and disable the add-ons in this window.

7. Then click the button with three horizontal dots on the add-on and click the "Delete" button in the list.

8. Click the "Delete" button in the confirmation pop-up window.

Method 6: Create a New Firefox Profile

The current user profile in the Firefox web browser may be corrupted; you can create a new user profile to fix the "Failed to load XPCOM" error.

Step I. Import Saved Bookmarks

As a first step, you need to import the bookmarks that you have saved in your current user profile to avoid data loss.

1. Open the Mozilla Firefox application.

2. Click the "Open application menu" button and select the "Bookmarks" option from the displayed list.

3. From the Bookmarks menu, select Manage Bookmarks at the bottom of the list.

4. On the Library screen, click the Import and Backup button on the menu bar and select the Export Bookmarks to HTML… option from the drop-down menu.

5. In the Export Bookmark File window, browse to and select a location, and then click the Save button to save the bookmark file.

Step II: Create a new user profile

This section will introduce the method to create a new user profile in the Firefox application to fix the "Failed to load XPCOM" error.

1. Launch the Firefox browser application.

2. Type about:profiles in the URL bar at the top and press Enter to open the About Profiles window.

3. Click the "Create a new profile" button in the window.

4. Then click the "Next" button on the "Welcome to the Create Profile Wizard" window.

5. Enter a name for the profile in the "Enter a name for the new profile" field and click the "Finish" button in the window to create the profile.

Note. Click the "Select Folder..." button to change the location where the user profile name is stored instead of the default location.

Method 7: Reinstall Firefox

The Firefox application installed on your computer may be corrupted or not installed correctly. You can reinstall Firefox on your computer to fix the "Unable to load XPCOM" error.

Step I: Remove Firefox

The first step is to uninstall the existing version of the Firefox web browser on your PC using the Control Panel.

1. Press the Windows key, type control panel and click Open.

2. Click the Category option in the View drop-down menu and click the Uninstall a Program option in the Programs heading.

3. Select Mozilla Firefox (x64 en-US) from the list, click the "Uninstall" button at the top of the panel, and click the "Yes" button in the UAC window.

4. Then click the "Next" button in the Mozilla Firefox Uninstall Wizard.

5. Next, click the Delete button in the next window.

6. Click the "Finish" button on the last window to completely remove the Firefox application.

7. Press Windows key + E at the same time to open File Explorer and navigate to This PC > Local Disk (C:) > Program Files > Mozilla Firefox.

8. Right-click the Mozilla Firefox folder and select Delete from the list to delete the files.

Step 2Reinstall Firefox

The next step to fix the "Unable to load XPCOM" error is to reinstall the Firefox web browser on your PC.

1. Press the Windows key, type google chrome and click open.

Note. You can use any web browser to download the Firefox browser on your computer.

2. Open the official website of the Mozilla Firefox browser in Google Chrome and click on the "Download Firefox" button in the window.

3. Double-click the downloaded Firefox Installer.exe executable file to launch the setup file.

4. Wait for the installation process to complete.

5. Launch the Firefox web browser on your PC.

Method 8: Change Tor Web Browser Settings

If you are using the Tor Web Browser, in addition to Firefox, problems in the Tor Browser can cause the "Failed to load XPCOM" error. To fix this error, you can try to check for problems in the Tor Browser with Firefox to fix the error.

1. Open the Firefox app.

2. Click the "Open application menu" button and select the "Settings" option from the displayed list.

3. On the "General" tab, click the "Settings..." button in the "Network Settings" section.

4. Select the Manual Proxy Configuration option in the Connection Settings window.

5. Enter SOCKS Host: 127.0.0.1 Port: 9050 in the HTTP Proxy field, enter 8080 in the Port field, and click OK.

6. Then type About:config in the Firefox browser search bar and click the "Accept the risk and continue" button.

7. Finally, type network.proxy.socks_remote_dns in the search bar and click the radio button to set the entry type to true.

8. Now type https://check.torptoject.org/ into the Firefox browser search bar and press the Enter key to check for problems with Tor Browser.

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The article discusses how to fix the "Unable to load XPCOM Firefox" error on Windows 10 PC. Try the methods in the article to fix the error and please leave your suggestions in the comments section. If you have any questions about the "Unable to load XPCOM" error, write them in the comments.