I was seeing an SSL error in Safari 6.1.6 (8537.78.2) on OSX 10.8.5 when visiting a website, and the debug information provided from the developer tools didn't indicate the source of the issue. The issue was reported by multiple users of OSX 10.8, and was resolved for those users by restoring TLSv1 in the server configuration (config change at bottom of question).
The error message in Safari developer tools was
Failed to load resource: An SSL error has occurred and a secure connection to the server cannot be made.
In Safari, there was no additional information under the "Requests > Network" tab (which I saw referenced on other answers). The information there seemed to relate to loading the content of the error message rather than the original site.
What other methods, if any, could I have used to extract a "server lacks TLSv1 support" message from Safari 6 / OSX 10.8.x?
Additional background info: The change required to the nginx server configuration was this –
-ssl_protocols TLSv1.1 TLSv1.2;
+ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
Best Answer
Safari 6.1.6 supports only TLS 1.0 (which is increasingly being turned off by servers concerned about the BEAST attack), and there's no error message apart from that generic "SSL error has occurred" in the Console. You'd need a newer version of macOS to carry on using Safari on those sites. If upgrading the OS is not an option (for example if you still need the older version of Xcode) then you could try Firefox 45.9.0 ESR, which uses TLS 1.2 (confirmed with www.HowsMySSL.com); that version of Firefox passed its end-of-life in mid-2017 (and more recent versions require a newer OS), but at least it's an improvement over Safari 6.1.6. However I'd be more comfortable installing a modern OS alongside the Lion / Mountain Lion, or at least using VirtualBox to run a modern version of GNU/Linux inside it, and using an up-to-date browser from there.