Since upgrading to Quantum I can't go to any website...blocked by Firefox. I am running version 59 for Mac with OSX High Sierra. The message I get is "The owner of www.xxxxx.com has configured their website improperly . To protect your information from being stolen, Firefox has not connected to the site. Invalid security certificate. Not only can I not connect to sites like AOL or Yahoo, I can't even connect to Mozilla (I am writing this on my old Windows 7 machine). I tried all of the suggestions for the problem that are listed on the site troubleshooting guide, but nothing works. This did not happen with previous versions of Firefox and other than this issue, nothing has changed on my Mac as far as settings or programs. The site suggests going to preferences-options-access security...but that does not show up on my FF menu, so I am screwed on that one. I have cleared my cache's, cookies, and such and rebooted several times to no avail. Any suggestions are welcome before I switch to Opera or another browser.