Hi

This support article should help;

https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect

Hi Paul Many thanks for this - I had already gone down this path, but the end result was unhelpful, and I was trying to find a fix to my problem other than the one on the site that you have identified. The problem was identified on this site as one where the page (in my case the bulk of the pages) that I was trying to access could not be shown as the Firefox browser couldn't verify the authenticity of the data that the websites were trying to send. The only solution offered was to contact the website owners to notify them of the problem (ie it was their problem, not Firefox's). This response was highly implausible (the sites I was trying to access were all for major, reputable and respected organisations/owners, including some of Firefox's own sites) and I wasn't about to waste my time and theirs by send them all emails alleging their problems, which was quite obviously not the case. In the absence of any other alternative, I deleted the Firefox app from my desktop and reinstalled it, which fixed the problem - this seems to me to be clear evidence that the problem lies with Firefox and not the pages that I was trying to access. I see and note from the various questions and proposed solutions on various other help sites/forums that deleting and re-loading Firefox sometimes doesn't fix this problem, but it sure did for me. Once again, thanks for spending the time to respond to my query and hopefully my "fix" may/can help others to fix the same problem.