I don't think so. Since Firefox 74, it is no longer possible to have an extension be automatically installed as part of another application install. See the Add-ons Blog for more information.

Many thanks for the reply.

As the former registry setting method no longer works as a method to automate installation of the Mendeley Firefox plugin - extension sideloading - what alternatives will work on large numbers of Windows 10 machines in our enterprise?

We currently have Firefox v 95.0.2 (64-bit).

I have tried the method of creating an "extension" directory for Firefox:

C:\Program Files\Mozilla Firefox\extensions

and using the xpi file, create a folder named after the GUID of the plugin, and copy unzipped contents of the xpi file to the folder.e.g.:

C:\Program Files\Mozilla Firefox\extensions\{5c0b10e0-c8b5-4014-8a6f-8f0196da7563}

This did not work.

I understand I could use a policies.json file to install a plugin, the json file located in the folder

C:\Program Files\Mozilla Firefox\distribution

I successfully tested this with an example from the web that sets the start page to a specific URL.

The mendeley firefox addon file is held in the location:

C:\Program Files (x86)\Mendeley Desktop\Firefox Importer\mendeley_web_importer-3.2.65-fx.xpi

I cant find any good practical examples of installing a plugin with a policies.json files, so can anyone let ne know what this should look like?

You can use GPO or a policies.json file to pre-install extensions. See "Extensions":

• https://github.com/mozilla/policy-templates

I will move the thread to Firefox for Enterprise support.