Sorry, hopefully this should provide more clarity.
It was not me that saw this but a client (A Domain Admin Owner) who had logged in and was attempting to go to use the File Manager - see my post about Bookmarks)
I then logged in as root (as normal) and then got the error in the other post. the error floored me.
I am assuming that it is possible for both “root” and a Domain owner to be logged in at the same time - they have separate accounts and user ID (0 vs 1001) we are in different locations after all.
the client is currently off the system and I can now access without any error. but cannot see why either should have occurred.
Thanks, but don’t think anything was moved or deleted by either the client or me. though the client may have deleted a bookmark as suggested by me. If @illia’s suggestion was valid - as that was what we had been discussing.