I can't install any add-on that's hosted outside of AMO nor in Firefox for Android 40.0.3, neither in Firefox Beta for Android 41. What I think should happen: I download signed .xpi-file (it saves automatically to sdcard), then open it with Firefox and Firefox should ask me if I want to install this add-on. What really happens: an add-on is downloaded, but when I open it's .xpi-file with Firefox - nothing happens. Firefox just shows me a blank screen (see the screenshot). My friend has this issue too. It seems like a regression bug (because I could install add-ons hosted outside of AMO with no issues in earlier versions), but I'm not entirely sure. So my question is: should I file a bug on Bugzilla or is there a way to install add-ons hosted outside of AMO to Firefox for Android and it's just me doing something wrong? My phone has Android v2.3.5. UPDATE: apparently, I can't install add-ons from local files, but can do from some certain sites. My add-on (which I have problem with) is hosted on Github, and I can't install it for reason unknown. UPDATE2: it seems like add-ons can be installed from Github if it's not just a file (because Github changed Content-Disposition of at least certain raw file types from "inline" to "attachment"), but a binary attachment of a "release".