Migrated (almost) successfully to Leap 42.3/KDE Plasma5. Most problems have been small, though I have run into a wall with KNotes.

KDE4 stored the note files in "~/.kde4/share/apps/knotes/notes/", along with the .ics files. KDE5 appears to not use that, and as it turns out, KDE4 somewhere along the line migrated the KNotes storage to Akonadi.

Three problems have arisen: 1) I cannot locate the stored notes under "~/.kde4/share/apps/knotes/notes/", or under "~/.local/share/Knotes/" or anywhere in "~/.config/";
2) the "Configure KNote" dialog will not show the folder location (other than "Notes"), nor allow the source folder to be changed; and 3) the destination folder for stored notes cannot be changed.

I have Google'd this, and turn up some older (pre-KDE5) items, and some Debian-based problems,

KNotes is not a show stopper, though I would like to avoid saving each note as a text file for subsequent import.