There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

http://kb.mozillazine.org/Error_loading_websites

https://www.bing.com/search?q=web+site+access+denied

https://support.mozilla.org/en-US/kb/what-does-your-connection-is-not-secure-mean

Often, "Secure Connection Failed" means "Connection Failed (trying to load a secure page)". In other words, not a security problem, just a connection problem.

Hi FredMcD,

Thanks for answering.

I have disabled the Antivirus and tested on different computers with fresh OS installed and all of them behaved the same way.

Thanks,

What is the URL of your website? Maybe someone here can figure out what the issue is.

Is there any additional detail on the error page about the reason for the failure to connect?

See also: Secure connection failed and Firefox did not connect

Otherwise, the URL would be very helpful.

Hi all,

Sorry for the late reply.

The only message that I receive is attached. There is no other error code being showed. Are there any other Firefox logs that I can have a look and try to gather more information?

Hi all,

Just wanted to say thanks for everybody and also the let you guys know that we found the issue.

We used the website https://www.ssllabs.com/ssltest/index.html which gave us some errors during the Handshake to establish the communication with the website, based on the error we noticed that the SHA Hash was not enabled on the servers, so after enabling it the issue was fixed.

I really appreciated the help from everyone.

Did they also popup a security certificate to accept to get to their site as well? Sometimes some site requires this and if you don't see or block that popup you can't access the site and get the screen that you posted.

I'm having the exact same issue on microsoft.com - something hasn't been right with Firefox since 56.0.2.

Hi Hyncharas, this thread is about the original poster's own website. Could you start a new thread about the problem you're having?

Also, some of these articles may be relevant:

• "Your connection is not secure" -- page generally has an "Advanced" button to get more technical information.
  • What do the security warning codes mean?
  • How to troubleshoot security error codes on secure websites

• "Secure Connection Failed" -- typically has scantier information about the problem and if the padlock appears normally, can be taken to mean "connection failed"
  • Secure connection failed and Firefox did not connect