Yeah, so if you set 'xpinstall.signatures.required = false' in the about:config it'll let you use your extensions, but this is just a workaround.

When a fix is fully rolled out (which should include Developer edition), then you won't need that (and probably should re-enable signature checking).

thanks . I have toggled that in about:config and extensions are back to working. internally, what does this toggle turn off?