Unable to boot Win10 after upgrade to VBox 6

[billziss]

Host: macOS 10.14.4
Guest: Windows 10 1803 and earlier versions
VBox: 6.0.4

I just upgraded to VBox 6.0.4 from VBox 5.x and I am no longer able to boot my Win10 VM. The Win10 VM boots to the Windows logo and then appears to hang (i.e. no boot progress is made after waiting for a long time). After manually powering off the VM a few times I am presented with the repair boot options. However Windows is unable to repair itself and is also unable to boot in safe mode.

I have tried booting Win10 1803 as well as previous versions of Win10 that I have available in my snapshots. I have tried various other troubleshooting steps without success. I attach a zip file that contains VBox.log and screenshots of some of the failure messages that I receive when trying to boot/repair Win10.

It is notable that VBox 6 works with a Win8 VM as well an elementary Linux and a FreeBSD VM.

I appreciate your help.

[socratis]

There's nothing out of the ordinary with your VM. Compared to my Win10-64 VM for example, here are our differences:

00:00:01.068063 [/Devices/serial/0/] (level 3)     <--- I have no serial port
...
00:00:01.068073 [/Devices/usb-ehci/0/] (level 3)   <--- I have USB3
00:00:01.068094 [/Devices/usb-ohci/0/] (level 3)
...
00:00:01.068113 VRamSize <integer> = ... 128 MB)   <--- I have 256 MB VRAM

but I don't think that these would make any difference at all, except maybe the serial, there's been a re-write of the serial ports part in VirtualBox 6.0.0.

00:00:01.203657 Host path '/Users/billziss', map name 'billziss', writable, automount=false, automntpnt=, create_symlinks=false, missing=false

Oh, BTW, I would strongly advice against sharing your home folder as a Read-Write one. If something goes bad in your guest, it has RW access to your data, not a good thing to have...