I cannot download any addons at all. Whenever I enter a query to search for one I absolutely know to exist, it takes a very long time (say, minutes) after which I get the message "could not find any matching add-ons". This also happens when I go to the addons website (rather than the built-in tab) and download an addon manually. It waits practically indefinately for the download to start. Not a single byte is being downloaded. This problem occurs on multiple machines that are on different internet connections. Also, the problem is not exclusive to Windows: Firefox for Linux also has this problem. It looks like the addons site is experiencing some kind of problem, rather than Firefox itself. Expectedly, updating addons also doesn't work in much the same way (waits forever). Just to be as complete as possible, this article... https://support.mozilla.com/en-US/kb/Unable%20to%20install%20add-ons?as=aaq ...does not provide a fix.