Ignore me friends, for I have broken the cardinal rule. If only I had performed a search before making this post, I would have found my answer here ([Solved] Workaround for upgrading over multiple Versions of MiaB to the latest when multiple major Versions of Nexcloud are included (first accured in upgrade from v0.30/v0.40 (NC13) to v0.42b (NC15) with v0.41 (NC14) between ) ! UPDATED! cose of backup)
Carry on. I am back up and running now.