Works for me with a http:// link. Firefox seem to be trying to upgrade the connection to secure HTTPS in your case and fails. This website only works via an HTTP connection and not via a secure HTTPS connection, so you need to override this. Do you have HTTPS-Only mode enabled ? Don't you get the choice to continue to the HTTP version of that web page ? Can you switch off HTTPS mode via the padlock ? *https://support.mozilla.org/en-US/kb/https-only-prefs You may have to use "Forget About This Site". You can remove all data stored in Firefox for a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History"). Using "Forget About This Site" will remove all data stored in Firefox for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose then make sure to backup this data or make a note. You can't recover from this 'forget' unless you have a backup of involved files. If you revisit a 'forgotten' website then data for that website will be saved once again. *https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox