Exactly, not in regular, in those builds the xpinstall flag is ignored. A lot of people recommend switching to Developer Edition to use unsigned extensions, bu

Exactly, not in regular, in those builds the xpinstall flag is ignored. A lot of people recommend switching to Developer Edition to use unsigned extensions, but that's aligned to the Beta update channel. There's no way to get stable releases + unsigned extensions. Whatever the security argument, I find this completely antithetical to user freedom, especially given that it's allowed in Chrome! I just can't believe that Mozilla is the one restricting their own users. (It's also news to me that unsigned extensions can be enabled in ESR, I thought it was just Nightly and Developer. That's nice I guess.)