It’s sometimes important to know how to install a Firefox theme or extension that is not compatible with current version of Firefox since it was made for an older version and developers didn’t bother to upgrade it to work with latest version of Firefox. There have been many solutions to put an expired extension of Firefox to work will all versions of the browsers; however I failed to find a way to install an incompatible extension or theme for Firefox. If an extension or theme is incompatible with current version for Firefox, “Add to Firefox” button will be disabled hence you will not be able to install that add on, instead Firefox will say “This add-on is for older versions of Firefox”. Did you know how to bypass Firefox version compatibility test? Probably no, but it’s simple to work the other way around, let’s see how. Follow these steps and install any theme and extension for any version of Firefox whether or not they are compatible:
- Install Nightly Tester Tools extension for Firefox
- Select the theme or extension you want to install and go it its page, e.g. https://addons.mozilla.org/en-US/firefox/addon/13232
- Copy this URL and open it in any other browser: IE, Google Chrome, Safari or Opera
- You will see “Download Now” button, right click on it and copy link address:
- Now go to Firefox and Paste the copied link address which will look like this: https://addons.mozilla.org/en-US/firefox/downloads/latest/13232/platform:5/addon-13232-latest.xpi?src=addondetail
- Hit Enter/Return and plugin install window will open:
- Install the Theme/Extension
When installation completes it warns you that this add on was not compatible with current version of Firefox.
- Click “Force Install”, it shows following window:
- Restart Firefox and you’re all set.
In case you want to put incompatible, installed extension or theme to work, read on.
To Install Incompatible Extension or Theme for Firefox:
To enable existing incompatible extensions and themes for Firefox:
- Go to Tools>Add ons
- Note that there will be button “Override all Compatibility” that enables all extensions
- If you want a single incompatible add on to work, right click it and select “Override Compatibility”
- Click “Force Install” and its enabled.
NOTE: Firefox doesn’t recommend using incompatible extensions and themes so you may try this at your own risk. Sometimes it works but sometimes it may result in crashes or problems with working of Firefox.