Firefox 42 will not allow unsigned extensions

It's the "no override" part that concerns me.

I created and maintain an extension that is used by visually-impaired people around the world (it has been translated by volunteers into Dutch and Chinese, for example).

Occasionally a Firefox update breaks this extension. OK, fine, that's the cost of doing business. Of course, the automated compatibility report that Firefox creates is utterly useless; it almost never catches the breakage. But that's a side rant....

There can be a decent turnaround lag (sometimes on the order of a few days) to get a new version of an extension reviewed by addons.mozilla.org. In the meantime, I have made a habit of building a new version of the extension and giving it to anyone who asks. Some people rely on it to use the web and can't wait for Mozilla to do their thing (another side rant: I once stupidly forgot to check in a key resource. I've since changed my development process to keep this from happening again. But the non-functional extension that I pushed passed Mozilla's review just fine. Makes me wonder how much value the review process is really adding.)

If I want to be able to continue this process, I will need to sign the extension myself (and who knows what histrionics Firefox will throw if a user tries to replace an extension with one that has the same UUID but a different signature!)

Hi, Mozilla developer here, speaking for only myself. I'm not sure why we don't make this clearer on the wiki page, but I think the reason there's no override is that any malware installation routine would simply activate it and continue on its merry way. (Disclaimer: I didn't work on this feature and am going by recollection and my own logic.)

We see many copies of Firefox infested with rogue add-ons the user didn't ask for or isn't even aware of. Sometimes these add-ons even ship with big-name software, with no opt out or with the opt out squirreled away in some dark corner. Typically, they do one or more of the following: (1) spy on the user, (2) add affiliate codes for money, (3) cause performance problems and crashes.

The network is a pretty hostile place these days. It's no longer 14-year-olds playing around for fun; there are moneyed interests in the game. And the sorts of people who don't frequent HN are pretty much helpless and clueless in the perpetual tug of war between various companies and mafias. As a "user agent", we have the opportunity defend users who lack the sophistication to root around and remove invasive software they didn't ask for.

Of course, if you're reading this, you're in a different category. You have a better idea which software to trust, and you know how to scour your machine if something gets past you. That's why nightlies and the Developer Edition let you do whatever you want: you aren't the ones who need hard-coded protections to shield you from pref-twiddling installers.

I hope that provides some needed context. Safe surfing, all!