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Couldn’t Load XPCOM: 4 Ways to Fix It in Firefox, Tor & Windows
Failed updates are the main cause of this problem.

- The Couldn't load XPCOM error message appears primarily because of a failed Firefox update.
- If you are dealing with this issue, the fastest solution is to switch to another browser.
- Creating a new profile can solve the Firefox error Couldn't load XPCOM in Windows.

- Easy migration: use the Opera assistant to transfer exiting Firefox data, in just a few steps
- Optimize resource usage: your RAM memory is used more efficiently than Firefox does
- Enhanced privacy: free and unlimited VPN integrated
- No ads: built-in Ad Blocker speeds up loading of pages and protects against data-mining
- Download Opera
Users reported Couldn’t load XPCOM error message on Windows 10 while trying to start specific applications, so let’s see if we can fix this problem.
Problems with Firefox, or other applications, will occur sooner or later, so it’s essential to know how to fix those problems.
What causes XPCOM errors?
XPCOM is short for Cross Platform Component Object Model, a cross-platform component model from Mozilla. Without it, Firefox cannot function properly, and it might be frustrating because you can’t use it to its full extent.
Here are a few known causes:
- Corrupted Firefox installation – A corrupt installation can prevent the XPCOM component from loading, causing this error.
- Conflicts with other software – Conflicts with software or extensions installed on the computer can also cause this error.
- Outdated or corrupted XPCOM components – Outdated or corrupted XPCOM components can also prevent the element from loading, causing this error.
- Incorrectly set Firefox profile – An incorrectly set Firefox profile can cause the XPCOM component to fail to load.
- Virus or malware – A virus or malware infection can damage the XPCOM components and cause this error.
- Problems with the Windows registry – Problems with the Windows registry can also cause the XPCOM component to fail to load, causing this error.
What are some common XPCOM errors?
The solutions listed below will also prove helpful if you are encountering the following issues:
- Couldn’t load XPCOM – Here is an error about the XPCOM missing.
- Firefox couldn’t load XPCOM – You will notice that this variation appears because of a failed update.
- Couldn’t load XPCOM Windows 10 – This variation is similar to the first error message.
- Firefox couldn’t load XPCOM Windows 10 – Also, this is similar to the other Firefox-related messages.
- Xulrunner couldn’t load XPCOM – This is an XPCOM error that can also appear on Mac.
- Couldn’t load XPCOM Firefox portable – This variation is the same as on the full version.
So, after clearing these things, let’s see how we can fix the Couldn’t load XPCOM error.
How do I fix Couldn’t load XPCOM?
Before going into solutions, note that if Firefox is giving you a hard time in general, and not just because of the XPCOM issues, then maybe you should consider using a different browser entirely.
We recommend you give Opera a shot. This web browser is built using the Chromium engine, just like Edge and Chrome, and it is highly stable and reliable, allowing for near-zero errors.
It also has some extra tools that most other browsers don’t accept through extensions, such as a built-in VPN and a very efficient ad-blocker.

1. Completely remove Firefox and reinstall it

- Follow the instructions on the screen to complete the process.
- Press the Windows key + E to start File Explorer , then remove these folders (for 32-bit and 64-bit versions): C:\ProgramFiles\Mozilla Firefox C:\ProgramFiles(x86)\Mozilla Firefox C:\Users\your_user_name\AppData\Local\MozillaFirefox C:\Users\your_user_name\AppData\Local\Mozillaupdates C:\Users\your_user_name\AppData\Local\VirtualStore\Program Files\Mozilla Firefox
After uninstalling Firefox and removing its installation directory, download and install the latest version of it.
Expert tip:
Some PC issues are hard to tackle, especially when it comes to corrupted repositories or missing Windows files. If you are having troubles fixing an error, your system may be partially broken. We recommend installing Restoro, a tool that will scan your machine and identify what the fault is. Click here to download and start repairing.
When the installation process is finished, start Firefox and check if the problem is resolved.
2. Create a new Firefox profile

- Click Next .

After creating a new profile, you must check if this problem is resolved. If everything works without a problem, just keep using your new Firefox profile, and everything should be in order.
Some of our readers also suggested removing your Firefox profile and creating a new one, so you might want to try that as well.
Firefox Not Working on Windows 10: 8 Fixes if It Won’t Open
Did not connect: potential security issue in firefox: fix, fix: firefox has disabled the ability to change some options, 3. delete everything from the temp folder and disable your antivirus program.
- Press Windows Key + R and enter %temp% .

- The Temp folder will now open.
- Select all files from the Temp folder and delete them.
Antivirus can sometimes interfere with specific applications and cause this and many other errors to appear; therefore, be sure to disable it and check if that solves the problem.
If disabling the antivirus doesn’t fix the problem, you might want to remove it and check if that solves this error temporarily.
4. Reinstall Thunderbird
Thunderbird is a browser that Mozilla also makes, and it has the same XPCOM component that may fail after an incomplete update.
As for its most famous brother , to fix this problem, Mozilla recommends a clean reinstallation of Thunderbird. After that, you can follow the same steps as in Solution 1.
That includes uninstalling the program, deleting its folder from the paths below, and reinstalling the app: C:\Program Files\Mozilla Thunderbird\ C:\Program Files (x86)\Mozilla Thunderbird\
Couldn’t load XPCOM error usually appears while starting Firefox, but in most cases, this problem can be fixed simply by reinstalling Firefox. If that doesn’t work, try any other solution from this article.
You may also find it helpful to read our guide on how to fix Firefox when it’s not responding in Windows 10/11 .
For suggestions or questions, feel free to use our comments section below.
Still having issues? Fix them with this tool:
If the advices above haven't solved your issue, your PC may experience deeper Windows problems. We recommend downloading this PC Repair tool (rated Great on TrustPilot.com) to easily address them. After installation, simply click the Start Scan button and then press on Repair All.
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Firefox XPCOM error Couldn't load XPCOM (Solved)
Firefox XPCOM error description: Firefox couldn't open and the following error is displayed on screen: "Couldn't load XPCOM". The XPCOM error, may caused on a Windows based computer whenever a user tries to open Mozilla Firefox after a Windows Update or if the Firefox's profile folder is corrupted. Firefox's profile folder corruption may happen after a virus attack or after installing a third party extension on your Firefox browser.

This guide contains instructions to resolve the "Couldn't load XPCOM" error on Mozilla Firefox browser.
How to FIX the "Couldn't load XPCOM" error in FIREFOX (Windows – All Versions).
Important: Before applying the instructions bellow to resolve the XPCOM Firefox problem, make sure that your computer is virus/malware free by following the steps in guide: How To Scan Your Computer for Viruses and other Malicious Programs (Malware Removal Guide).
Method 1. Reinstall – Upgrade Firefox to the latest version.
1. From another Web browser (e.g. Internet Explorer, Chrome) download and Install the latest version of Firefox on your system. *
* Note: Do not uninstall Firefox, just run the Firefox Installer and follow the on-screen prompts to repair/upgrade the current Firefox application.
- Firefox Download.
Method 2. Start Firefox in Safe Mode and Disable Firefox's Extensions (Add-ons).
1. Start Firefox in Safe Mode by following this procedure:
- Hold down the SHIFT key and then double click to open the Firefox application.
- Choose Start in Safe Mode

2. If Firefox starts without the XPCOM error message, then probably a Firefox extension (add-on) causes the "Couldn't load XPCOM" error. At this case, disable one-by-one the installed Add-ons and then close and start Firefox normally, until you find out which plugin causes the problem.

- At Extensions pane, Disable the installed Add-ons, (one every time) and then restart Firefox normally until you find out which extension causes the XPCOM problem.

- When you find out which Firefox extension causes the problem, then remove it completely (by starting Firefox in Safe mode).
– If after disabling all plugins, the XPCOM error persists then reset Firefox to Default Settings by applying the steps in next Method.
Method 3. Reset Firefox Settings to Default (Refresh Firefox).
1. Start Firefox in Safe Mode .
2. Choose Refresh Firefox .

3. Choose Refresh Firefox again. *
* Note : The refresh Firefox feature restores all browser settings to default, by creating a new user profile and by removing all Firefox's Add-ons (extensions) and customization (preferences, plugins, added search engines). The Firefox Refresh doesn't remove these items:
- Browsing history
- Open windows and tabs
- Web form auto-fill information
- Personal dictionary

Method 4. Uninstall and Re-install Firefox from your System.
Finally, if none of the above methods resolves the XPCOM error when starting Firefox, then:
1. Backup your Firefox Passwords, Bookmarks, Settings, etc .
2. Completely remove Firefox application and folders from your computer.
3. Install the latest Firefox version .
4. Restore your Firefox settings.
Method 5. Restore Your Computer To An Earlier Working State by using System Restore.
1. Try to restore your computer to a previous working state in order to resolve the XPCOM error in Firefox.
- How to Restore Windows 10, 8 or 8.1 to a previous working state
- How to Restore Windows 7 or Vista to a previous working state.
That’s all folks! Did it work for you?
Please leave a comment in the comment section below or even better: like and share this blog post in the social networks to help spread the word about this.
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10 comments.
Kristina July 11, 2018 @ 10:10 am
I've already purchased AVG and don't want to pay twice to have it downloaded. Please. It's on my file under my email. Thanks Krissy
Lakonst2013 July 11, 2018 @ 1:28 pm
@Kristina: Use another browser (e.g. Chrome or Internet Explorer) to access your email and to get the "Activation Code" for the AVG.
Karlene P. Grinnell November 4, 2018 @ 8:47 pm
Instead of trying to "REPAIR" Firefox, CAN I DOWNLOAD CHROME…WITHOUT first removing / doing anything with FIREFOX?
Lakonst2013 November 5, 2018 @ 11:20 am
@Karlene P. Grinnell: Of course
David Kit Friedman December 5, 2018 @ 9:15 am
Method 1 of reinstalling worked fine for me.
Julian Opificius May 8, 2019 @ 3:49 am
Methods 1-4 didn't work for me, but after step 4 I discovered that the program started OK when double-clicking the icon on the screen (without resorting to safe mode) but NOT by clicking once on the icon on quick-start bar – strange. I deleted the icon on the quick-start bar, restarted FF from the icon on the main window – allowing the icon on the quick-start bar to reestablish itself, and everything is now back to normal.
BF7 July 13, 2019 @ 1:13 am
With the new version of Firefox (68.0) upgrading doesn't work because it won't share data with older versions due to tighter security protocols. So what do you do, I had lots of extensions and xpcom also prevented Firefox from loading in safe mode?
What did was to save the relevant C:\Users\%username%\AppData\Roaming\Mozilla\Firefox\Profiles\ folder as backup (I didn't need it). Uninstall any versions of Firefox you have on your pc using the standard Microsoft uninstaller. Download the previous version (67.0.4) and install it. I unchecked the mozilla maintenace option to limit its capacity to upgrade in the background. It picked up the data from corrupted installation and everything is now back and working. If it doesn't work try downloading at the installing the 32 or 64 bit version instead.
Dash February 19, 2020 @ 6:08 am
Thanks! Problem fixed with easy-clear instructions
Tom Wayburn May 24, 2020 @ 7:25 am
I paid for another year of Vipre; but, due to a non-standard distribution of software and data on my three internal drives, I ended up without a working copy of Vipre. I downloaded the free version of Malwarebytes, which found 178 PUPs or worse. By the time, I had solved my virus problem, Firefox was no longer in evidence. I do not recall uninstalling it. In any case, with no further changes, the XPCOM problem was solved. I will reinstall Firefox (67.0.4) when time permits. Thanks to all.
AMeSh May 14, 2021 @ 5:53 am
After updating the portable version of Firefox, this message began to go out. In safe mode it does not start. Firefox disappointed unpleasantly. In the pit!
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Firefox always say: Couldn't load XPCOM !
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This thread was archived. Please ask a new question if you need help.

- 7 have this problem
- 21353 views
- Last reply by jscher2000 - Support Volunteer
4 years ago

Hello supporters
I've restart my pc then run firefox and it show up message Couldn't load XPCOM
I've uninstalled it many times
Then delete all file from my pc belongs to firefox And the problem still exist
I've deleted from roaming, local, programs files, register And still same problem
I've used software for complete uninstallation for firefox and the problem still exist
Please tell how to fix this problem ?
I discarded all files belongs to firefox but it show up same message every time I run it and I can't browse any page from it
Chosen solution
This issue would normally be fixed with a clean reinstall that involved deleting the Firefox program folder.
- (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
- (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"
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 can do a clean reinstall to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.
You can find the full version of the current Firefox release (61.0.1) in all languages and all operating systems here:
- https://www.mozilla.org/en-US/firefox/all/
- https://www.mozilla.org/en-US/firefox/61.0.1/releasenotes/
All Replies (6)
What OS are you running, Linux or Android ?
Reinstall with Current Release Firefox 61.0.2 with a Full Version Installer
- https://www.mozilla.org/firefox/all/
If that does not fix the issue the issue is in your Profile : Make a new one and test ...:
- https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
If is your Profile :
- https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
- http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox
Do the above with Firefox closed. Work with Copies only, do not transfer the problem into the new Profile.
What's What in the Profile :
- bookmarks and history: places.sqlite
- bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
- cookies.sqlite for the Cookies
- formhistory.sqlite for saved autocomplete Form Data
- logins.json (passwords) and key4.db (58+) or key3.db (57 and older) (decryption key) for Passwords saved in the Password Manager
- if you only have key3.db then make sure to remove an existing key4.db
- cert9.db (58+) or cert8.db (57 and older) for (intermediate) certificates stored in the Certificate Manager
- if you only have cert8.db then make sure to remove an existing cert9.db
- persdict.dat for words you added to the spelling checker dictionary
- permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
- sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)
Please let us know if this solved your issue or if need further assistance.
My OS is Windows 10 64bit
I have deleted all files of firefox even profile
And I've been installing version 62.0.2 64bit
I've created new profile and still same problem
I don't know what should I do please help me
- Top 10 Contributor
Chosen Solution
I was able to solve the 'xpcom missing error' I got for a long time as Thunderbird wouldn't start when my computer started.
Open the 'Task Manager' on the menu by right clicking in Windows 10 task bar, next to the empty space on the bar showing the time and date.
On the task manager menu top menu click startup, right click on Thunderbird and select "Open File Location". If the File Explorer opens on C:\Users\(Your PC Name) \AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup, delete the Thunderbird file there.
Then, open in File Explorer the C:\Program Files (x86)\Mozilla Thunderbird directory. Find the application Thunderbird (.exe) and right click on it. Click "Create Shortcut" and confirm to place the shortcut on the desktop. Cut paste the Thunderbird - shortcut file from the desktop to C:\Users\(Your PC)\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.
This worked for me after trying all the options of deleting and install/uninstalling the software and registry etc.
If any help on above kindly email me on [email protected]
An 'xpcom missing error' is always a problem with files in the Firefox program folder and is usually caused by security software that is locking files and preventing Firefox from replacing all the files.
You always have to remove the Firefox program folder and possibly disable your security software or boot Windows in Safe Mode to get a clean reinstall. Your steps may have worked if you rebooted a few times in case an update didn't complete properly.
Hi kamleshbarot, this happens to be a Firefox thread, but you can find Thunderbird threads mentioning XPCOM using this search:
https://support.mozilla.org/search/advanced?q=%22xpcom%22&product=thunderbird&sortby=1&a=1&w=2
Fix: Couldn’t Load XPCOM
The error “ Couldn’t load XPCOM ” is usually caused by Windows Updates. Though there are several methods on the internet to fix the issue the one in this guide is by far the easiest I’ve found.
In order to proceed with this method, you will need to use Internet Explorer (that is there by default, or another browser if you have it installed)
If you cannot locate/find Internet Explorer, simply Hold the Windows Key on your keyboard and press R to open the run dialog, and in the run dialog type -> iexplore.exe and click OK.

Method 1: Simply Upgrade/Reinstall
This method has worked for most of the users and it is very easy to follow. Once you’re in Internet Explorer or another browser, simply head over to the following address to download the latest setup file for Firefox, run it and install. https://www.mozilla.org/en-US/firefox/new/?product=firefox-3.6.8&os=osx%E2%8C%A9=en-US
Method 2: Back up and do a Clean Install
Before you begin, if you would like to Back Up Firefox and you can also choose to export certain things such as your history, passwords or bookmarks and you can import these bookmarks later from Chrome or other browsers.
1. Download the 30-day trial version of RevoUninstaller by going to www.revouninstaller.com and clicking the following button on the site
2. Now you should have the Revo setup file, open it and install it. After it has been installed, you will have the RevoUninstaller icon on your desktop. Open Revo Uninstaller, and select Firefox,
3. Now click Uninstall and then select Advanced and follow the prompts on the screen to uninstall Firefox.
4. Then select Advanced and Click Scan on Revo Uninstaller.
5. Next screen will present you with Leftover files, see the screen below, select all of them and click Delete.

6. Then, go to C:\Program Files first , and delete the Mozilla Firefox folder and also check C:\Program Files (x86)\..
7. Press “Windows’ + “R” and type in “%temp%”.
8. Press “CTRL” + “A” and then press “Shift’ + “Delete” to clear this folder.
9. Reinstall Firefox and check to see if the issue persists.
Note: If this is happening on the Tor browser, run it as an administrator and try disabling your antivirus temporarily. It is also recommended to uninstall Geforce Experience if you have it installed on your computer because it is known to cause conflicts with the application in certain cases.
Method 3: Run as Administrator
In some cases, the issue is simply fixed by running the browser as an administrator. Administrative Privileges are required by some Softwares to pass certain hardware/security limitations. Therefore, in this step, we will be running the browser as an administrator and then check if that fixes the issue. For that:
- Right-click on the browsers executable on the desktop.
- Click on the “Properties” option and then select the “Compatibility” tab.

- Run the browser after that and check to see if the issue persists.
Method 4: Using Firefox for Tor Network
In some cases, this issue occurs with the Tor browser and doesn’t seem to go away using any workaround/fix. Therefore, in this step, we will be using the Firefox browser to connect with the Tor browser instead of the Tor browser itself. This fix works for most users and is really easy to apply. In order to do so:
- Download and install the Mozilla Firefox browser from here .
- Now, navigate to the Tor browser installation folder which is usually on the desktop and its address should look something like this. Desktop\Tor Browser\Tor (full path "C:\Users\your-username\Desktop\Tor Browser\Tor")
- There should be a “tor.exe” at the bottom of the folder, right-click on this executable and select “Pin to Taskbar”.
- Now, startup Tor and wait for it to fully connect to its network.
- After Tor is started, launch the Firefox browser that we just installed not from inside the Tor bundle but the standalone browser that we installed in step 1.

- Click on the “Network” tab and then select the “Settings” option.

- Click on “OK” to save your changes.
- Type in “About:config” in the address bar and verify the “ I’ll be Careful ” prompt.
- Type in “network.proxy.socks_remote_dns” in the search bar and toggle it to be TRUE.
- Restart Firefox and enter the following in the address bar. https://check.torproject.org/
- It should now say that you are configured to run Tor.
- The issue should now be fixed completely.
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Windows Computer Error Cannot Load XPCOM 2018
by Affordable Computer Repairs on November 25, 2018 in Computer Tips
How to Fix the Cannot Load XPCOM message in 2018
Cannot Load XPCOM error is usually caused by a corrupted or missing dynamic-link library (DLL) file or files. Errors related to it usually occur when a program does not handle the file during use. This common problem happens within the Windows registry, where applications look up the location of DLLs they need to operate. Because these are critical files, when one becomes unavailable (corrupted, missing or the wrong one), all sorts of things can go wrong.
Common issues are program lock-ups, slow PC performance, system freezes, blue screen errors (BSOD), startup or shutdown problems, and installation errors. In the worst-case scenario, if the DLL is required by Windows, your entire system could become unstable or unbootable.
We would advise against fixing Cannot Load XPCOM errors manually. In doing so, it could take several hours, do more harm than good, and end up not even resolving the underlying problem.
Some people may recommend, as a solution, for example, downloading a program such as “Advanced System Repair Pro”. The problem with this approach is the possibility that the software program can do more harm than good. Programs such as “Advanced System Repair Pro” run a variety of troubleshooting and diagnostic tests on your computer in order to pinpoint and fix almost all known issues. If you wish you can read some more information and the practical use of this software.
Cannot Load XPCOM and Firefox
We have seen the error “Cannot load XPCOM” with the following program: Firefox. Firefox couldn’t open and the following error is displayed on the screen: “Couldn’t load XPCOM”, usually in a box in the middle of the screen. The XPCOM error is caused on a Windows-based computer whenever a user tries to open Mozilla Firefox after a Windows Update or if the Firefox’s profile folder is corrupted. Firefox’s profile folder corruption may happen after a virus attack or after installing a third-party extension on your Firefox browser.
How to Fix the Problem In Firefox
Below we list several options to correct this problem;
Option1. Reinstall – Upgrade Firefox to the latest version
From another Web browser (e.g Chrome, Edge or Internet Explorer) download and install the latest version of Firefox onto your computer.
Do not uninstall the present version of Firefox, just run the Firefox Installer and follow the on-screen prompts to repair/upgrade the current Firefox application.

Option 2. Start Firefox in Safe Mode and Disable Firefox’s Extensions (Add-ons)
Start Firefox in Safe Mode by following this procedure:
Hold down the shift key and then click or double click the Firefox icon to start the application. Then choose the “Start in Safe Mode” button.
If Firefox starts without the XPCOM error message, then it is probably a Firefox extension (add-on) which is causing the error message (“Cannot load XPCOM”). As this may be the case, disable each “add-on” one-by-one then close and start Firefox normally. With all “add-ons” disabled try to start Firefox again.
If Firefox starts with no error message go back into “Start in Safe Mode” and enable each “add-on” one by one until the problem is found. After each enables you would need to shut down Firefox and then restart Firefox. A little time consuming but there is no other thorough way to do it.
To disable a Firefox “add-on” from the main screen, click on the 3 horizontal bars on the right and then click on the jigsaw piece which says “Add-ons”
At the Extensions windows (under the tab Add-ons Manager) disable all items. Probably best not to remove any at this stage. The “bad add-on” can be removed later when it is determined which it is.
So having disabled and then enabled “add-ons” the problem can be found and when the error is again displayed you will need to start Firefox in “Safe Mode” again.
If after disabling all “add-ons” the problem still there then go to Option 3 below.
Option 3. Reset Firefox Settings to Default
Start Firefox in “Safe Mode” as before then click the “Refresh Firefox” button instead of the “Start in Safe Mode” button. This refreshes Firefox.
It is suggested by Mozilla that you refresh Firefox a second time. So do as they say.
When refreshing Firefox what will happen is:
- Firefox browser settings are set to default
- A new user profile is created and all “add-ons”, plug-ins, search engines are removed. So any customisation is wiped out in other words.
- What a refresh does not do is: remove Bookmarks; Browsing History; Passwords; Cookies; web form auto-fill information and personal dictionary.
Option 4. Uninstall and Re-install Firefox on your computer
If none of the above options resolves the XPCOM error when starting Firefox, then:
- Backup your Firefox Passwords, Bookmarks, Settings and anything else you may need.
- Completely remove Firefox with its folders from your computer
- Download and install a new version of Firefox
- Restore your Bookmarks etc as above.
Option 5. Restore Your Computer To An Earlier Working State by using System Restore
- By using System Restore you can try to restore your computer to a previously working state in order to resolve the XPCOM error in Firefox. We don’t cover using Microsoft System Restore in this article, please see that article on our website.
- Using System Restore (accessed through the Control Panel; System and System Protection) will undo any changes you have made to the computer in the last xx days. Xx being today’s date and the date of the System Restore point. This method can have advantages and disadvantages so “think before you leap”, you can do significant damage to your Operating System.
- In some instances where Hard Disk space is at a premium a System Restore point may not be available.
Option 6. Ditch Firefox and use something else
Other browsers available for a Windows computer are Chrome, Safari, Edge, Internet Explorer or Opera.
Do you still want help? If you live in Brisbane, you can bring your computer, laptop or Mac to us at 48 Octantis Street, Brisbane, you may want to check our repair rates which I am sure you will find, as most of our customers do, are in fact quite affordable. Please contact us on 3397 1215 or 0409 974 707 before you arrive.

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Fix Mozilla Firefox Couldn’t Load XPCOM Error on Windows 10

Mozilla Firefox is a trusted Web Browser and is compatible with most devices. However, the Couldn’t load XPCOM error message pops up now and then. The XPCOM is a cross-platform component model from the Mozilla Firefox, so the Cannot load XPCOM error disrupts the browsing. You may click on the OK button to close the error message, but you may not be able to use the Firefox app. The article addresses the error and the methods to resolve the XPCOM Firefox error are explained here.

How to Fix Mozilla Firefox Couldn’t Load XPCOM Error on Windows 10
The list of causes for which the XPCOM error occurs on Firefox is given in this section.
- Outdated Firefox- The outdated version of the Firefox app may cause this error.
- Corrupt Firefox User Profile- The User Profile on the Firefox Web Browser may be corrupt or may have malware sources.
- Third-party Extensions on Firefox- The issue with the XPCOM may arise if there are third-party extensions installed on the Firefox app.
- Corrupt System Files- The System files installed locally on your PC may have been corrupt or the PC may be infected with a virus.
Method 1: Basic Troubleshooting Methods
The first approach to solve the Couldn’t load XPCOM error is to try the basic troubleshooting methods listed in this section.
1. Restart PC
There might be some glitches on your PC that prevent you from using the Firefox browser; you can restart your PC to fix the error. Press the Windows key, click on the Power button at the bottom-left corner, and click on the Restart option to restart your PC.

2. Check Internet Connection
An unstable Internet connection may hinder you from using the Firefox browser. You can check the speed of the connection using the Speed test and assess its quality.

- If the speed is low, try using any other Wi-Fi network for browsing on Firefox.
- Consider changing the data plan of the Internet Connection to a better plan.
3. Switch to Another Web Browser
If the XPCOM error with the Firefox Web Browser is still not resolved, you can try switching to another Web Browser like Google Chrome. Follow the steps below to switch to a different browser:
1. Launch Settings by pressing Windows + I keys together.
2. Click on Apps setting.

3. Click on Default apps on the left pane.

4. Scroll down and click on the current Web browser .

5. Choose from the option as per your preference.

Also Read: How to Fix Firefox Not Loading Pages
4. Delete Temporary Files
The numerous temporary files saved locally on your PC may have disrupted the browsing activity on Firefox. You can read the method to delete the temp files on your PC using the link given here.

5. Repair Corrupt Files
The files on your PC may be corrupt and have some issues which may cause the Couldn’t load XPCOM error. Read the article to repair system files on Windows 10 for corrupt files using the link provided here.

6. Update Windows
In most instances, using an outdated OS may cause issues on the PC; you need to update the Windows on your PC to the latest version to fix this error. Read the article on how to update Windows on your PC using the link given here.

7. Run Windows Update Troubleshooter
The issues with the Firefox browser can be cleared by using the Windows Troubleshooter on your PC. Read the method to run the Windows Troubleshooter using the link here and fix the error.

8. Disable Antivirus Temporarily (If Applicable)
The third-party security services on your PC may disrupt you from using the Firefox app; you can disable the anti-virus program to fix this error. Implement the steps given in the link here to disable the Anti-virus software on your PC.

9. Perform System Restore
If the Firefox app performed better on the previous version of the Windows PC, you can try performing a System Restore on your PC to fix the error. The link which is given here will provide you with the method to perform a System Restore on your PC.

Also Read: Fix Your Connection is not Secure Error on Firefox
Method 2: Run Firefox as Administrator
The Couldn’t load XPCOM error might appear if the Firefox is not granted the administrative permissions on your PC. You have to run the Firefox app as an Administrator on your Pc to fix the error.
1. Press the Windows key , type firefox and click on the Run as administrator option.

Method 3: Update Firefox Browser
Using an outdated version of the Firefox Web Browser can be a reason for this error. Follow the steps below to update the Firefox app on your PC.
1. Hit the Windows key , type Firefox and click on Open .

2. Click on the Open Application Menu button (indicated by the three horizontal lines) at the top-right corner of the home page and click on the Settings option on the list displayed.

3. In the General tab, click on the Check for updates button in the Firefox Updates section.

4. You will see the Firefox is up to date message on the Firefox Updates section.
Note: If there is an update for the Firefox browser, you will be prompted accordingly.

Method 4: Refresh Firefox Browser
To fix the Couldn’t load XPCOM error on the Firefox app, you can refresh Firefox entirely.
1. Launch the Firefox app from the Windows Search bar.

2. Next, click on the Open Application Menu button and click on the Help option on the list displayed.

3. Click on the Troubleshoot Mode… in the Firefox help window.

4. Now, click on the Restart button on the Restart Firefox in Troubleshoot Mode pop-up window.

5. Click on the Refresh Firefox button on the Open Firefox in Troubleshoot Mode confirmation window.

6. Then, click on the Refresh Firefox button on the Refresh Firefox to its default settings window.

7. Finally, click on the Finish button on the Import Complete window to Refresh Firefox completely.

Also Read: Fix Server Not Found Error in Firefox
Method 5: Disable Firefox Extensions
The extensions on the Firefox Web Browser can be a reason for the Couldn’t load XPCOM error. You can disable the extensions on the browser to fix the error.
1. Open the Mozilla Firefox app from the Windows Search bar.

2. Click on the Open Application Menu button and click on the Help option on the list displayed.

3. Now, click on the Troubleshoot Mode… in the Firefox help window.

4. Click on the Open button on the Restart Firefox in Troubleshoot Mode pop-up window.

5. Next, click on the Open Application Menu button and click on the Add-ons and themes option on the list.

6. Click on the Extensions tab on the left pane of the next window and toggle off the add-ons on the window.

7. Then, click on the three horizontal dots button on the add-on and click on the Remove button on the list.

8. Click on the Remove button on the confirmation pop-up message window.

Method 6: Create New Firefox Profile
The current User Profile on the Firefox web browser may be corrupt; you can create a new User Profile to fix the Couldn’t load XPCOM error.
Step I: Import Saved Bookmarks
As a first step, you need to import the Bookmarks you have saved on the current User Profile to avoid any loss of data.
1. Open the Mozilla Firefox app.

2. Click on the Open Application Menu button and click on the Bookmarks option in the list displayed.

3. In the Bookmarks menu, click on the Manage bookmarks option at the bottom of the list.

4. In the Library screen, click on the Import and Backup button at the menu bar and click on the Export Bookmarks to HTML… option in the drop-down menu displayed.

5. In the Export Bookmarks File window, browse and select a location, and click on the Save button to save the bookmarks file.

Step II: Create New User Profile
This section will introduce the method to create a new User Profile on the Firefox app to fix the Couldn’t load XPCOM error.
1. Launch the Firefox browser app.

2. Type about:profiles in the URL address bar at the top and press the Enter key to open the About Profiles window.
3. Click on the Create a New Profile button on the window.

4. Next, click on the Next button on the Welcome to the Create Profile Wizard .

5. Type a name for the Profile in the Enter new profile name field and click on the Finish button in the window to create the Profile.
Note: Click on the Choose Folder… button to change the location for storing the User Profile name instead of the default location.

Also Read: Fix Firefox is Already Running
Method 7: Reinstall Firefox
The Firefox app installed on your PC might be corrupt or not properly installed. You can reinstall Firefox on your PC to fix the Couldn’t load XPCOM error.
Step I: Uninstall 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 on Open .

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

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

4. Then, click on the Next button in the Mozilla Firefox Uninstall wizard.

5. Next, click on the Uninstall button in the next window.

6. Click on the Finish button on the last window to completely uninstall the Firefox app.

7. Press the Windows+ E keys together to open the File Explorer and navigate to the This PC > Local Disk (C:) > Program Files > Mozilla Firefox folder.

8. Right-click on the Mozilla Firefox folder and click on the Delete option on the list to delete the files.

Step II: Reinstall Firefox
The next step to fix the Couldn’t load XPCOM error is to reinstall the Firefox Web Browser on your PC.
1. Hit the Windows key , type google chrome and click on Open .
Note: You can use any web browser to download the Firefox browser on your PC.

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

3. Double-click on the downloaded executable file Firefox Installer.exe to run the installation file.

4. Wait for the installation process to complete.

5. Launch the Firefox Web Browser app on your PC.

Also Read: Fix No Sound in Firefox on Windows 10
Method 8: Modify Tor Web Browser Settings
If you are using the Tor Web browser, in addition to Firefox, the issues on the Tor browser may cause the Couldn’t load XPCOM error. To fix this error, you can try checking for the issues on the Tor browser using Firefox to fix the error.
1. Open the Firefox app.

2. Click on the Open Application Menu button and click on the Settings option on the list displayed.

3. In the General tab, click on the Settings… button in the Network Settings section.

4. Select the Manual proxy configuration option on the Connection Settings window.

5. Type SOCKS Host: 127.0.0.1 Port: 9050 in the HTTP Proxy field, type 8080 in the Port field, and click on the OK button.

6. Then, type About:config on the search bar of the Firefox browser and click on the Accept the Risk and Continue button.

7. Finally, type network.proxy.socks_remote_dns in the search bar and click on the toggle button to set the type of the entry to be true .

8. Now, type https://check.torptoject.org/ in the search bar on the Firefox browser and press the Enter key to check the issues with the Tor Browser.
Recommended:
- How Do I Set Up A Second Venmo Account
- Fix Chrome Not Saving Passwords in Windows 10
- How to Disable Split Screen in Safari
- Fix Firefox PR END OF FILE ERROR in Windows 10
The article discusses the methods to fix couldn’t load XPCOM Firefox error on Windows 10 PC. Try implementing the methods discussed in the article to fix the error and please leave your suggestions on the same in the comments section. If you have any queries on the Cannot load XPCOM error, post them in the comments.

Elon Decker
Elon is a tech writer at TechCult. He's been writing how-to guides for about 6 years now and has covered many topics. He loves to cover topics related to Windows, Android, and the latest tricks and tips.
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How to Fix Couldn’t Load XPCOM on Firefox? [7 Easy Tricks]
Couldn’t load XPCOM is a common error experienced by the users when opening Firefox on a Windows computer.
Many users reported, “I can’t open Firefox, it says couldn’t load XPCOM.” and looking for solutions to fix it on their Windows system.
Well, the Firefox XPCOM error is generally caused by the Windows updates, and there is a possibility that after installing the update the Firefox profile folder gets corrupted and causes the error.
Many users managed to fix the error, after upgrading Firefox to the latest version and creating a new Firefox profile. (Follow detailed steps below)
So, keep reading the article to learn how to fix it completely, but first, have a look at some of the common reasons responsible for the error.
Why I am Getting Couldn’t load XPCOM Error?
Commonly after installing the Windows update, the XPCOM error appears , but there are other reasons as well.
- If the Firefox profile folder gets corrupted then this can cause can’t load XPCOM error.
- Your system is infected with virus or malware
- Installing third-party extensions on the Firefox browser can also cause the problem.
Now, follow the fixes given one by one, till you find the one that works for you.
How Do I Fix Firefox Couldn’t Load XPCOM Error?
Table of Contents
Solution 1 – Upgrade Firefox to Latest Version
This solution worked for many users to fix the error, here it is suggested to avoid uninstalling the present Firefox version .
Open another web browser like Chrome, Microsoft Edge, or Internet explorer and download the latest Firefox installer .
Follow the on-screen instructions and repair or upgrade the already installed Firefox application on your system.
Hope this works for you to fix the error, but if not then follow the next solution.
Solution 2 – Start Firefox in Safe Mode & Disable Firefox’s Extensions (Add-ons)
If you are still getting errors on your Firefox browser , then here it is suggested to start Firefox in safe mode and disable Firefox’s extension (add-ons).
Follow the steps to start Firefox in Safe Mode:
- Press the SHIFT key > double click to open the Firefox application.
- Now select Start in Safe Mode

If Firefox starts without the XPCOM error then possibly the Firefox extension (add-on) are causing the error. Disable the installed add-ons one by one to find out which plugin is causing the problem.
For disabling the Firefox plugin > choose Add-ons from the main menu.
- At Extensions window > disable the installed Add-on (one only) > restart Firefox . Follow the same steps till you find out which extension is causing the problem.

- And as you find the one that is causing the error, then remove the add-on completely.

Moreover, if disabling the entire plugins won’t work for you to fix Firefox error then try the next solution.
Solution 3 – Reset Firefox to Default (Refresh Firefox).
Try refreshing the Firefox as this restores entire browser settings to default , by creating a new profile and uninstalling all the installed extensions (add-ons) as well as customization (like plugins, preferences, added search engines).
Follow the steps to do so:
- Start Firefox in Safe Mode . (As shown in the above steps)
- Now select Refresh Firefox > select Refresh Firefox

And check for the Couldn’t load XPCOM error is fixed or not.
Solution 4 – Uninstall Firefox & Reinstall it
If upgrading Firefox to the latest version won’t work for you then here it is suggested to uninstall it completely and reinstall it.
Just uninstalling Firefox is not enough, to fix the problem, it is suggested to completely remove the files related to Firefox.
Well, you can do this easily by using the third-party uninstaller. This removes the program completely along with the junk files, registry entries, and much more.
Get Revo Uninstaller to Uninstall Firefox Completely
Moreover, if you are looking to remove everything manually then follow the steps to do so:
- If using 32-bit Windows 10 version then remove C:\Program Files\Mozilla Firefox
- If using 64-bit Windows version then remove C:\Program Files(x86)\Mozilla Firefox
Many users also recommended removing the below given folders from the system:
- C:\Users\your_user_name\AppData\Local\MozillaFirefox
- C:\Users\your_user_name\AppData\Local\Mozillaupdates
- C:\Users\your_user_name\AppData\Local\VirtualStore\Program Files\Mozilla Firefox
And after uninstalling Firefox as well as removing the installation directory, restart your Windows system.
Now download the latest Firefox version and install it and as the installation process is completed start Firefox and check if the error still appears or not.
If still getting the error then follow the next solution.
Solution 5 – Create New Firefox Profile
If the above solution won’t work for you then here it is suggested to create a new Firefox profile . As sometimes installing the latest updates causes the error. This worked for many users to fix the error.
- Hit Windows Key + R and in the Run box > type firefox.exe –p > hit Enter

- Now click the Create Profile button > click Next .

- Then type the name of your new profile > click Finish
- You can also set the storage directory for this profile .

- And choose the new profile > click Start Firefox

Now check if the Firefox XPCOM Error, is fixed or not. If the error won’t appear then keep using the new Firefox profile.
But if the error still persists then try removing the Firefox profile completely and creating a new one. It is worth giving a try as this may work in your case.
Solution 6 – Delete the Temp folder
Follow the steps to delete the temp folder as this might be one causing conflict.
- Press Windows Key + R > in Run box > type %temp%.

- Next click Enter
- In the Temp folder > select all files and delete
After deleting the files check if the error is resolved or not.
But if not then check if you are running a third-party antivirus program then disable the security program temporarily. If this works for you then well and good but enable the antivirus program.
Solution 7 – Run as Administrator
Some users also managed to fix Firefox Couldn’t Load XPCOM error , by running the browser as an administrator.
So follow the steps to run the browser as an administrator:
- On the desktop > right-click on the browser’s executable.
- Then click on the Properties option > choose the Compatibility
- And in the compatibility tab > check the Run this Program as an Administrator option > click on Apply > OK

- Next, run the browser and check if the issue is resolved.
It is estimated now is resolved and you start using it again. But if not then the only option left is to switch to another browser like Google Chrome, Microsoft Edge, Opera, etc., and start using it.
Recommended Solution – Fix Various Windows 10 PC Errors/Problems
If your Windows 10 PC is running slow or causing various errors then here it is suggested to simply scan your system with the PC Repair Tool .
This is an advanced multifunctional tool that is designed to fix various PC issues and errors. Not only with this, but you can also fix other computer errors like DLL errors, BSOD errors, prevent file loss, protect your computer from virus or malware infection, repair registry entries , and much more.
It also repairs the corrupted and damaged Windows system files to improve PC performance like a new one.
Get PC Repair Tool, to Fix Make your PC or Laptop Error Free
Conclusion:.
Couldn’t Load XPCOM is an irritating Firefox error, and usually appears while starting Firefox. But luckily many users fixed the error by following the fixes given.
Here I tried my best to list down the best possible solutions to resolve Firefox Couldn’t Load XPCOM error in Windows 10.
Follow the solutions given carefully and start using Firefox with ease. You can also check our Browser Issues Hub to check other issues related to Google Chrome and other browsers .
Hope you liked the article and if there is anything that I missed out on or you have any other suggestions or queries then feel free to share with us.
You can also write to us on our Facebook page and share your love by hitting the Like button.
Good Luck..!
Hardeep has always been a Windows lover ever since she got her hands on her first Windows XP PC. She has always been enthusiastic about technological stuff, especially Artificial Intelligence (AI) computing. Before joining PC Error Fix, she worked as a freelancer and worked on numerous technical projects.
Firefox couldn’t load XPCOM in Windows 11/10
Firefox couldn’t load xpcom.

1] Start in Safe Mode and see
2] create a new firefox profile, 3] reset firefox, 4] uninstall and reinstall firefox.
Also delete the following folders if you see them on your computer. The may be hidden folders and you may have to unhide them via Folder Option:
[email protected]

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Fix: Couldn't load XPCOM issue in Mozilla Firefox · Fix 1 – Refresh Firefox · Fix 2 – Create a new Firefox profile · Fix 3 – Uninstall Firefox and
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