How to Disable Thunderbird Add-on Compatibility Checking

Thunderbird Add-on Icon Logo

Mozilla’s Thunderbird compatibility checking can prevent your add-ons from installing. You can disable it to allow add-ons to bypass this protection.

While it might protect users from fatal errors due to incompatible plugins, Thunderbird’s add-on compatibility checking feature can also be a huge annoyance. In particular, if you’re running the Beta channel of Thunderbird nearly all add-ons will throw up this problem and won’t be allowed to install.

Sometimes you can manually force the plugin using the “Install Anyway” button, but in my experience that button rarely works. The ultimate way around it is to completely disable compatibility checking, and here’s how to do it.

thunderbird add-ons

First, you need to know the exact version number of Thunderbird that you have installed. This can be found by opening the Help > About Thunderbird menu. Underneath the bold Thunderbird title will be the version number, at the time of writing this the beta channel was currently in version 19.0. The full “19.0” must be recorded, not just 19.

find thunderbird version

Next open the Tools menu and click Options…

tools options

In the Advanced > General tab of options, click the “Config Editor…” button.

advanced general config editor

An about:config window will open with a Warranty warning. The whole warranty deal is just for fun (there isn’t really a warranty), so click the “I’ll be careful, I promise!” button to continue.

void your fake warranty

The preference that you need doesn’t exist yet, so you’ll need to create it. Right click either an empty area, or the Preference Name box and then select New > Boolean.


In empty boolean value box Type in the following code, with the exact version substituted for the # signs. If the version has a “.0” or “.1” after it, be sure to include it.

  • extensions.checkCompatibility.#.#

For example, I’m running the beta channel version 19.0, so I put in:

  • extensions.checkCompatibility.19.0

new boolean value

Next right click on the newly created preference and select Toggle so that the value is set to false. Done!

config preferences

Now you can install any add-on you want regardless of version incompatibility. This doesn’t mean that all plugins will work with your current version, but chances are most of them will.

install add-ons



  1. mariano

    February 8, 2014 at 8:41 am

    This does not work for me with Thunderbird 24.2.0. I set the boolean but the add-on will not be installed, and the usual error message shows.

    • Just

      August 24, 2015 at 9:59 am


  2. GratefulDeed

    December 2, 2015 at 4:20 pm

    Thanks for posting this, exactly what I was looking for.

  3. Martin

    January 27, 2020 at 1:30 am

    This does not work for me with Thunderbird 68.4.2. I set the boolean but the add-on will not be installed, and the usual error message shows.

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