Firefox logo
Categories: developers releases

Support for extension sideloading has ended

Today marks the release of Firefox 74 and as we announced last fall, developers will no longer be able to install extensions without the user taking an action. This installation method was typically done through application installers, and is commonly referred to as “sideloading.”

If you are the developer of an extension that installs itself via sideloading, please make sure that your users can install the extension from your own website or from (AMO).

We heard several questions about how the end of sideloading support affects users and developers, so we wanted to clarify what to expect from this change:

  1. Starting with Firefox 74, users will need to take explicit action to install the extensions they want, and will be able to remove previously sideloaded extensions when they want to.
  2. Previously installed sideloaded extensions will not be uninstalled for users when they update to Firefox 74. If a user no longer wants an extension that was sideloaded, they must uninstall the extension themselves.
  3. Firefox will prevent new extensions from being sideloaded.
  4. Developers will be able to push updates to extensions that had previously been sideloaded. (If you are the developer of a sideloaded extension and you are now distributing your extension through your website or AMO, please note that you will need to update both the sideloaded .xpi and the distributed .xpi; updating one will not update the other.)

Enterprise administrators and people who distribute their own builds of Firefox (such as some Linux and Selenium distributions) will be able to continue to deploy extensions to users. Enterprise administrators can do this via policies. Additionally, Firefox Extended Support Release (ESR) will continue to support sideloading as an extension installation method.

We will continue to support self-distributed extensions. This means that developers aren’t required to list their extensions on AMO and users can install extensions from sites other than AMO. Developers just won’t be able to install extensions without the user taking an action. Users will also continue being able to manually install extensions.

We hope this helps clear up any confusion from our last post. If you’re a user who has had difficulty uninstalling sideloaded extensions in the past, we hope that you will find it much easier to remove unwanted extensions with this update.

3 comments on “Support for extension sideloading has ended”

  1. Steve wrote on

    If anything this post exacerbates the confusion. According to the following site there are two ways to sideload an extension, install from file or install to folder:

    My understanding is that only the second method of sideloading is going away and that users can still manually sideload XPI files (I tested in 75b2 and it still seems to work). However this post is titled: “Support for extension sideloading has ended”. So which is it?

    I feel this is especially important because removing the first method would be anti-user, while removing the second method is (arguably) pro-user. The response to the first post announcing this was a whole lot of anger from a perceived anti-user move but I still don’t know if that was justified because you continue to be vague and contradictory about exactly what is and isn’t being removed. Please just spell out whether manual installation from a file will be supported going forwards.

    1. Caitlin Neiman wrote on

      Yes, you will still be able to manually install .xpi files.

  2. zakius wrote on

    how do you exactly achieve that? some local signing or what? cause app running on the same machine can pretty much do everything you can and sideload anyway