title: How to disable the incompatible add-ons prompt at Firefox start?
body: <p>I'm running some Robot Framework integration tests with Firefox 21.0 for Ubuntu. Recently my Firefox was updated and now it always pops up a prompt about incompatible add-ons when it starts. That's unacceptable, as then the tests cannot continue. The prompt looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/qKqGi.png" alt="The annoying prompt"></p>
  
  <p>There are several instructions about this on the web, but they are all either for some old version of Firefox or for some similar but not the same situation (like when Firefox asks whether to disable 3rd party plugins), or they require one to disable the compatibility check for each version of each add-on separately, so none of them seem to work. How do I get rid of the prompt for good?</p>