Disable Firefox Add-on Compatibility Checking

By on November 19, 2011.     2 Comments

This article is updated for Firefox 28, but won’t work this way for Firefox 29. Read more for info.

In an article I wrote last April concerning the Firefox 4 add-on compatibility checker, I explained how to quickly disable said tool in order to allow older add-ons to run. That tutorial worked great for Firefox versions 4-7, but it has to be updated for Firefox 8. In this tutorial, I’ll walk through removing the old configuration and adding the new.

  • 1.) Open up Firefox’s Configuration page by typing about:config in the address bar. Read the prompt and click the button saying you’ll be careful. (See how to re-enable that warning prompt)
  • 2.) Inside the filter field, enter in extensions.check to shorten the list of preferences
  • 3.) Right-click the extensions.checkCompatibility.4.0 preference and choose the Reset option. You will notice the Type changes from a boolean (True/False) to a string and the Value goes blank.
  • 4.) Create a New > Boolean with a preference name extensions.checkCompatibility.28.0 and set the boolean value to False.
  • 5.) Restart Firefox and your new preference will function just as it did for Firefox 4-27. The old preference you reset also disappeared from the Configuration page because it was an empty value.

Notice: Starting with FF 8, the old Preference needs to be removed and a new Preference with the proper major version number needs to be added each time Firefox updates. If Firefox goes from version 28 to 28.0.1, no change; if it goes to 28.1 or 29.0, you need to apply the change.

Posted in: Web Browsers



is the site owner of Computer Tech Tips and is passionate about computer technology, particularly Windows-based software, malware removal, and web development. He enjoys helping people troubleshoot computer problems and providing technical support to family, friends, and people around the net. Xps wrote 79 article(s) for Computer Tech Tips.


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Comments (2)

  1. April 30, 2014 at 4:04 am
    Xps said:

    This tip as it is only worked for Firefox versions 8-28. Things changed (again) with Firefox 29 and this tip no longer applies. Unfortunately, without disabling add-on compatibility checking, some other adjustments from my article “Make Firefox 4+ Look Like FF 3.6” won’t work either.

    I’ll continue to try and find solutions, but it seems Mozilla and their open-source community are intent on making more problems, and they can’t all be solved without significant help.

    If you have a solution, please get in contact with me.

  2. July 18, 2014 at 9:09 pm
    Xps said:

    I have since migrated to Pale Moon full-time. It is a web browser based on Firefox with all the security updates, but retains the nicer layout.

    I haven’t been able to get this particular computer tech tip figured out in Pale Moon (any assistance?), but I also haven’t needed to.

    With the current generation of Gecko-based browsers, there are a few other differences between Pale Moon and Firefox that are more obvious and not just “under the hood”: contrary to what Mozilla has done with their redesign of the user interface, Pale Moon will continue to provide a familiar set of controls and visual feedback similar to previous versions, including grouped navigation buttons of a decent size, a bookmarks toolbar that is enabled by default, tabs next to page content by default (easily switchable) and not in the least a functional status bar and more freedom in customization, to name a few things.

    Pale Moon is, and will always be, completely FREE to download and use! (Freeware)

    http://www.palemoon.org/
    http://www.palemoon.org/screenshots.shtml
    http://www.palemoon.org/layout-differences.shtml

    At least try the portable version out to see how you like it. http://www.palemoon.org/palemoon-portable.shtml

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