I get a message that reads

Security Error

The server could not prove that it is forums.opera.com; its security certificate is not trusted by your device's operating system. This may be caused by a misconfiguration or an attacker intercepting your connection.

You should not proceed, especially if you have never seen this warning before for this site.

(There is a button for proceed anyway and one for go back.)

The reason I presume it has to do with cloudfront is because of something I read on Slashdot recently, that cloudfront was going to continue to support both old SSL and updated, switching between the two based on sniffing the device being used (the justification being that many older devices exist on which one can't upgrade the SSL client) - I'm presuming they are coming to the wrong answer for my devices. (One uses Lollipop, the other Marshmallow).

Seeing as Leo (properly) closed the thread people were posting about this in as it was for a different topic and as I can now (since installing updates yesterday) reproduce the error myself ... here is a new thread to post about it in. If you're encountering this problem, please include your device OS (probably Android, but perhaps iOS too) and version, so we can tell cloudfront what to look for. (If it is cloudfront, those of you in Europe may not see it.)