I transfered a macOS Mojave 10.14.3 VM from Parallels 13 to VirtualBox. VB is the latest version 6.0.4 running on an iMac with the same OS.
When I boot the EFI loads an show the message "Press esc in 5 seconds to skip startup.nsh or any other key to continue". There is also a short message appearing that says something like "Boot error" or similar. But that's too short to recognise. I can type exit to enter the BIOS, but I have no idea what to do. Does someone have an idea? BTW, I transferred a Windows 10 VM from Parallels 13 the same way and it's working fine. Trying to install a new Mojave VM results in the same state.
I attach the log file for those who can read it

Thank you very much!
Thomas