Comment 33 for bug 861664

Just to be clear, I ran into this too. Its not uncommon for Firefox to state that some addons are "incompatible", and it will, usually, update some of them, when installing the new version. In my case, I got a list, which I mostly didn't pay attention to, except that I know it included Linkification (self adjusted, because its one of those that half the time doesn't update at all), and HTTPS-Everywhere, which I very recently added. I don't know if Noscript was "in the list" or not, but a number where listed as, "Current version is not compatible, check for updates?" As soon as the client loaded, every single thing that was in that list was just flat missing. Once I "installed" another plugin, as suggested by someone here, and restarted, they all reappeared.

It should be noted that, for me, installing a new Noscript "failed" to make this happen, or make it reappear, I had to install a completely different plugin, picked semi-randomly out of the ones available. So, something in the process of checking for compatibility and updating the list of new versions to load, failed. Its possible it effected only very recent additions, since it killed ones that I installed and/or manually updated, the last time I got such an update message as well. Everything installed "prior" to that update, stayed. And I know Noscript updated since then, I added the HTTPS one after that, and I also hand patched Linkification, to make it compatible (since I didn't figure what it did what likely broken between versions). I will bet donuts to dollars that everything else listed was in the same category, with the exception of a few that really are out of date, and I just haven't gotten rid of (or can't... I just love ones that refuse to let you uninstall them...).