Yeah, I know that. As I wrote before I was able to upgrade my 3.15 version to 4.2 by upgrading in steps: 3.15 -> 4.0 -> 4.2. The 3.15 -> 3.17 -> 4.0 ->4.2 way was one of my trials of the upgrade and I noticed this thread. I needed to do that as a direct upgrade from 3.15 to 4.2 throws errors about not existing user table when trying to log in (server starts, I didn't check logs thoroughly). I don't know if it should be supported as, as you said, it's very old version upgrade ;-)
I made some tests and was not able to replicate problem with upgrading 3.15 -> 4.2. It works as expected now, so I think we can forget about this issue.
Yeah, I know that. As I wrote before I was able to upgrade my 3.15 version to 4.2 by upgrading in steps: 3.15 -> 4.0 -> 4.2. The 3.15 -> 3.17 -> 4.0 ->4.2 way was one of my trials of the upgrade and I noticed this thread. I needed to do that as a direct upgrade from 3.15 to 4.2 throws errors about not existing user table when trying to log in (server starts, I didn't check logs thoroughly). I don't know if it should be supported as, as you said, it's very old version upgrade ;-)