[Fix] Some Extensions are not Allowed in Firefox 115 and Later

If you installed or upgraded to the new Mozilla Firefox 115 or later version and you are getting “Some extensions are not allowed” error message on Extensions panel or flyout (puzzle piece toolbar icon), this article will help you in fixing the issue and enabling the blocked extensions again in Firefox web browser.

Some Extensions are not Allowed Error Displayed on Extensions Panel in Firefox

When you click on the puzzle piece icon on Firefox toolbar to access Extensions panel, you receive following error message with an exclamation (!) mark icon displayed at the top of the flyout menu:

The incompatible extensions detected by this new feature are automatically disabled or blocked from running on the website.

New Quarantined Domains Feature in Firefox Causing the Error Message

The “Some extensions are not allowed” error message is shown by a new feature called “Quarantined Domains” introduced in Firefox 115 version. According to Mozilla team, this new back-end feature has been implemented to only allow some extensions monitored by Mozilla to run on specific websites for various reasons, including security concerns.

Mozilla team is working on improving this functionality and more options will be provided to users to manage these restrictions for each individual add-on in future versions of Firefox.

How to Disable Quarantined Domains Feature in Firefox and Enable Blocked Extensions?

If one or more extensions installed in your web browser have been blocked by this new feature and you want to use those extensions, you can disable the new feature and re-enable those disabled extensions in Firefox.

Mozilla team has provided a hidden secret preference/flag to turn off new Quarantined Domains feature in Firefox. Once you modify this preference/flag, the new feature will be disabled and all your blocked extensions will start working again.

Following steps will help you in disabling Quarantined Domains feature and re-enabling blocked extensions in Firefox web browser:

1. Open Firefox and type about:config in the addressbar and press Enter. It’ll show you a warning message, click on “Accept the Risk and Continue” button. It’ll open Firefox’s hidden secret advanced configuration page i.e. about:config page.

2. Now copy and paste following piece of code in Search filter box:

By default, the preference is not present and you’ll need to manually create the preference as mentioned below.

3. Select Boolean option and click on (+) button to create the required preference.

Now double-click on extensions.quarantinedDomains.enabled preference and set its value to false. Alternatively, you can click on the Toggle icon given next to the preference name.

4. You’ll need to restart Firefox to apply the changes. If you have opened multiple tabs and you don’t want to lose them, you can restart Firefox without losing tabs using methods given in following tutorial:

[Tip] How to Restart Mozilla Firefox Without Losing Tabs

That’s it. Restart Firefox browser and the new Quarantined Domains feature will be deactivated permanently in your Firefox browser.

Now open Extensions panel and all your installed extensions will start working again. The “Some extensions are not allowed” error message will disappear from the Extensions panel.

PS: In future, if you decide to restore the Quarantined Domains feature again in Firefox, set the above mentioned preference to true or delete the preference.

UPDATE: Firefox 116.0 and Later Allow Extensions to Run on Restricted Sites

Mozilla has introduced a new option “Run on sites with restrictions” on extension’s settings page in Firefox 116 and later versions. Users can now enable any particular blocked extension and allow it to run on websites by opening Add-ons Manager (about:addons) page and setting the “Run on sites with restrictions” option to “Allow“.

Also Check:

Disable or Remove “Extensions” Button from Firefox Toolbar [UPDATED]

[Tip] Disable or Remove “Firefox View” Tab Icon from Toolbar

[Tip] Remove Tabs Search (Arrow Button) from Firefox Title Bar