Firefox recently stopped supporting an out of date and insecure version of the Transport Layer Security (TLS) protocol. For websites that only support this insecure version of the protocol, Firefox will not connect. These websites should update their severs to a newer secure version of TLS to be compatible with Firefox.

patblackmore334 said

t This problem arose after your last security update, every thing else is fine. I can contact the St James bank site on my laptop, it was not updated. I have contacted the bank by telephone and they suggest using another browser which is not so convenient for me. There is obviously a problem which I hope you are able to solve

Thank you, I will contact sjp bank

The website may try to fallback to TLS 1.0 in a way that is no longer allowed in current releases or may be using a deprecated cipher suite.

You can open the about:config page via the location/address bar and use its search bar to locate this pref:

• security.tls.insecure_fallback_hosts

You can double-click the line to modify the pref and add the full domain (TEXT) to the value of this pref. If there are already websites (domains) in this list then add a comma and the new domain (no spaces). There should only be domains separated by a comma in the Value column (example.com,www.example.com).

If this helps then you can contact this website and ask them to look into this and update their security.

• https://developer.mozilla.org/en-US/Firefox/Releases/36/Site_Compatibility#Security
• https://developer.mozilla.org/en-US/Firefox/Releases/37/Site_Compatibility#Security