OSX VirtualBox VM inaccessible on 6.1.4 r136177 (Qt5.6.3)

I could not find a mac related post, so I wrote a new one, hoping that somebody can help me. The issue: I can´t remember any crashes or problems like system shutdown etc. but my Virtual Box VM is called "inaccessibel" and even after using the "prv" file instead of the broken "vbox" file (I kept an instance of both original files) and the attempt to load it into the Manager ... it remains inaccessible. I copied the error message in here (below). If the multiple log files (see the screenshot) could be helpful as well - let me know. As this is my financial "brain", I am starving for help.

Thank you in advance,

Julius

Premature end of data in tag VirtualBox line 8. Location: '/Volumes/VIRTUAL BOX/WIN 10 Videodesign Berlin/WIN 10 Videodesign Berlin.vbox', line 73 (8), column 28. /Users/vbox/tinderbox/mac-rel/src/VBox/Main/src-server/MachineImpl.cpp[503] (nsresult Machine::initFromSettings(VirtualBox *, const com::Utf8Str &, const com::Guid *)).

Fehlercode: NS_ERROR_FAILURE (0x80004005) Komponente: MachineWrap Interface: IMachine {85632c68-b5bb-4316-a900-5eb28d3413df} Callee: IVirtualBox {d0a0163f-e254-4e5b-a1f2-011cf991c38d}

GUI VM inaccessible

VM Folder with attempts to use the bckp- "prv"- file