what's your e-mail adres?

can you send and receive emails?

secure connection failed is not a big problem if the unsecured connection works

There can be many different reasons why a certificate warning appears. In any case, one shouldn't simply attempt to create an exception, but investigate the real issue. The problem can also be caused by malware. See this article for more information. https://support.mozilla.org/en-US/kb/add-security-exception

Please post a screenshot of the error message. It should give the exact cause of the problem. http://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

what's your e-mail adres?

One should never post the email address in a public forum. And this question shouldn't be asked in the first place.

secure connection failed is not a big problem if the unsecured connection works

This is utterly nonsense.

I have suddenly started getting the same issue

https://support.cdn.mozilla.net/media/uploads/images/2015-11-06-01-50-49-7c10c9.png

Any help would be appreciated

Thanks

Paul-H,

Please start a new thread for your problem with the information you posted above. Provide as many details as possible.