I believe I’ve got the website issues fixed.
Ubuntu compiled MySQL 5.7 differently than MySQL 5.6. Specifically, they included four things that were plugins into the base server.
When the upgrade installed it, it asked me whether I wanted to keep the original configuration or accept a new configuration. I opted to keep the original as I have a number of site specific things configured in.
Also the plugins were kept in a table, mysql.plugins, and so in spite of having these functions compiled in, it also tried to load these plugins. As you can imagine, this did not go over well.
So I have deleted those plugins which are now hard coded into the server from the plugin table, and fixed the configuration issues.
Another issue was that 5.7 now has support for encrypted connections but you have to specify a certificate and key to use them. It is supposed to disable this functionality if none are found, but instead it tried and bitched about it.
So I’ve now configured in the ability to support encrypted sessions.