Created attachment 8750743 [details] rect21.png Don't really have any more information than that. There's nothing unusual about this extension, it doesn't happen in a clean profile, nothing unexpected happens if I turn on AOM logging.
Dave, who can investigate this more and/or is there anything we can get from the 'broken' profile to clarify what is going on here?
Just realized that maybe Mossop isn't available (leaving ni in case I misremembered). Andy, are there other folks who could help?
The daily add-on update check just ran (I guess the first time since b3 was installed) and now the extension is disabled.
We'll look in the regular weekly add-ons manager triage, next one is tomorrow. Could you attach the add-on from your profile to the bug so we can see how its signed please?
Also look in about:config and see if any of the xpinstall preferences are non-default.
This isn't worth pursuing. The problem has gone away and is unlikely to happen again. But to answer your questions, the add-on is not signed at all, and xpinstall.signatures.required is set to false.