How do you deploy plugins for Firefox 40+?
Answers (1)
Some useful links which had helped me earlier for installing xpi.
Check global install in the below link.
http://kb.mozillazine.org/Installing_extensions
Using Registry method ( Note: Xpi has to be extracted first)
https://developer.mozilla.org/en-US/docs/Adding_Extensions_using_the_Windows_Registry
Also check this link.
https://support.mozilla.org/en-US/questions/991798
Or else Install the plugin and copy the folder(%appdata%\Mozilla\Firefox\Profiles\profile.default\extensions to another machine. still it will prompt for installation. To avoid it change this.
%appdata%\mozilla\firefox\
user_pref("dom.ipc.plugins
This method also worked for me.