Thanks for your input. I did install the current version, but initially I couldn't get it to run normally - it would crash while still loading and initializing. So I re-installed the older version, which would at least run successfully, but was missing my bookmarks and other data. And of course, I couldn't log in to sync with it. It just didn't seem likely to me that the login page might have been purposely deleted so recently, and I couldn't imagine anything else that could have changed to be so incompatible with the earlier version that it would crash the program. As it turned out, apparently the URL did change. After my post, I re-installed the new version and eventually managed to get it working. I discovered that the login page URL it took me too was https://auth.opera.com/account/authenticate/email, so I guess it did change. It had a little trouble getting logged in, but eventually it got there and things seem to be working, at least for the moment.
