This article may help. https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect You could try clearing the cache plus cookies and site data (the latter meaning you will have to log in again). https://support.mozilla.org/en-US/kb/how-clear-firefox-cache https://support.mozilla.org/en-US/kb/clear-cache-without-clearing-browsing-history https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox There is also a way to tell Firefox to forget about a site. You right-click a relevant entry in history and select "Forget About This Site". That may result in losing your log-in details so you should record your user name and password first.