How can I force Firefox Quantum (v 60) to use cached content after going offline? Suppose I go offline. Some kinds of webpage are retrieved from cache when I hit the back button – for example, Wikipedia pages. Other kinds of webpage, however, are not retrieved from cache: instead I get the message 'Offline mode. Firefox is currently in offline mode and can't browse the Web. Press "Try Again" to switch to online mode and reload the page' with the "Try again" button. I imagine that the pages that don't get retrieved from cache are those that have a "no-cache" tag or tag with a short expiration time. To try to bypass this I set browser.cache.check_doc_frequency to 2, which should force Firefox to always retrieve from cache, and restarted. But the problem with those pages still remain when going offline. I also tried to increase the cache size (both disk and memory), but to no avail. Both kinds of cache are enabled. I remember that with older versions of Firefox there was a combination of settings or an add-on that forced Firefox to retrieve from cache when offline (browser.cache.check_doc_frequency = 2), and to behave "normally" (browser.cache.check_doc_frequency = 3) when online. No such add-on seem to exist for Firefox Quantum (no surprise). I've searched the web for similar questions and I found several suggestions, but they refer to older versions of Firefox and don't seem to work with Quantum. Does anyone know how to solve this problem with Firefox Quantum? Cheers!