Do you use Library backup and restore? If not, how do you move MC's library data from one version to the other?
Yes. He does. He meant, "I don't speak for JRiver on what may or may not be supported".
There is no other good way to backup Library Data. You can, of course, just copy the files on disk yourself, but this has three issues:
* You can't include Settings this way, only the Library itself (and this even misses "library-specific" settings like Auto-Import entries).
* You must close MC first entirely, or ensure it is not using the Library in question, or your backup can be left in an inconsistent state (and
will restore read-only).
* When you restore the Library, it will restore with the same UUID, which means if you use it to "clone" a Library, it can cause havoc with Library-specific settings (like auto-import entries).
A Library Backup includes
all relevant settings and Library files that are not machine specific (which are all generated when you install the application anyway). The only thing it doesn't include is the media files themselves, which would make the Library Backup huge (and is typically better restored, when needed, via a different mechanism anyway).
When you go from major version to major version, some settings
may not migrate properly (if they were changed substantially). It almost always works perfectly, but there have been exceptions here and there. One example from recent times is the top/bottom Toolbars. The storage system for these was changed (in v19, I think, but it may have been in v20) and so if you restore from a v18 backup to v21, you might not get your toolbar icons back (or they may come back all messed up).
Restoring on the same version will always include all of the settings that matter, though. If you find any specific thing where this isn't true, then that's probably a bug and you should report it. That is absolutely the goal of the Library Backup system.