MySQL upgrade to 8

I have tried and followed a few MySQL upgrade posts to (what should be a simple task).

https://tastethelinux.com/upgrade-mysql-server-from-5-7-to-8-ubuntu-18-04/N

The whole thing is now screwed and I cannot access MySQL on this server.

Advice please on to how reset this and access the server remotely - I noted that there was no longer a cnf file after running commands on this post.

Basically what I am asking is how to fully purge my sql and install it with version 8 and find the cnf file to make it remote accessible

On occasion, you can install a package from another (more recent) version of Ubuntu. But the more complicated the package, the more dependencies it will have. And upgrading just that package will cause a cascading effect that will require you to install these dependencies. And you're more likely to break your system than get the upgrade you want.

Of course, this is not specific to Ubuntu. If you had Microsoft Windows from 2011, no one would expect you to be able to run Microsoft Office from 2021. And we can't expect either Microsoft or Ubuntu to permit this level of compatibility -- it would be a lot of work.

My feeling is that MySQL probably has a lot of dependencies. Looking at this list, it looks like MySQL 8 is part of Ubuntu 20.04. It might be more work and you could affect other systems, but in the long run, upgrading your OS will give you a more stable system than upgrading just MySQL. Especially if you think you've made a mistake already.