Add-on ‘Disabled Add-on fix’ fixes deactivated extensions in Firefox 47-56

Mozilla[German]In older versions of the Firefox browser, add-ons could no longer be activated. The Mozilla developers have released an add-on for the Firefox browser to fix the problem that older add-ons are disabled in the browser.


The add-on bug in Firefox

On Saturday, May 4, 2019, Firefox is causing issues with add-ons on all platforms and in all versions. Some already installed add-ons were suddenly disabled. The background was an expired certificate that developers must use to sign certain add-ons. Starting with Firefox version 57, only those addons based on WebExtension APIs will work. What was planned as a security feature bricked many addons due to the expired certificate.

Firefox: Download fehlgeschlagen. Bitte überprüfen Sie ihre Verbindung

I’ve blogged about that within my article Firefox: Expired certificate disables addons (May 4, 2019).

Mozilla’s developers quickly acknowledged the problem – as the above tweet signals. Later they released updates for Firefox version 66.0.4 and 66.0.5 to fix the issue. For older Mozilla versions there was no update available to reactivate add-ons.


Add-on fix in older Firefox versions

Mozilla has now released the Firefox add-on Disabled Add-on Fix for Firefox versions 47 – 56. This extension again activates the extensions that were deactivated on May 3, 2019 for Firefox versions 47 – 56 by the expired certificate. This extension installs a new security certificate so that the extensions and designs for Firefox versions 47 to 56 can be reactivated.

Please note: If you install this extension and then upgrade to a newer version of Firefox (version 57 or higher), please uninstall this extension as it may not be compatible with updated versions. (via

Similar articles:
Firefox: Expired certificate disables addons (May 4, 2019)
Fix für Firefox Addon-Problem und ‘Der Download ist fehlgeschlagen’
Firefox 66.0.4 and 60.6.2 ESR fixes Add-on issue
Tor-Browser 8.0.9 released (May 7, 2019)
Firefox 66.0.5 and 60.6.3 ESR

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