Win10 guest won't boot anymore. Display-related.

[mat.tabasko]

Hello,

My Windows 10 VM won't boot anymore since a few hours. No new updates have been applied to the host OS.
What i'm seeing is the window logo showing up with the circular animation under it, then after a few seconds the circular animation freezes and massive glitches appears on my VM screen.

Here is what I see :

screenshot

glitches.jpg (118.33 KiB) Viewed 3357 times

I've let it like that for a few minutes thinking it was temporary and the boot was continuing in the background, nothing changed.
I also have a warning bubble with the following message :
"The virtual screen is currently set to a 24bit color mode. For better performance please change this to 32bit. This can usually be done from ...."
I never had this message before so I'm not sure it's the cause or a consequence of my issue.
I feel however that my issue is "diaplay-related" because on some occasion (and only when i'm not in full screen mode) i can reach the Win10 "boot recovery" menu.
From there I'm able to boot in safe mode.

I've place the logs of the startup in the attachments.

Anyone has a clue of what's happening?

Thank you.

[mpack]

The message means what it says. The guest has been configured for a 24bit (3 bytes per pixel) color mode (specifically 1024x768x32bpp). The host is configured for a 32bit (4 bytes per pixel) color mode. By itself this will cause poor performance because every pixel needs to be up converted, but then you also enabled 3D acceleration in the guest (i.e. pipe the data directly to graphics hardware), and that will pretty much kill it off.

I would try turning off 3D acceleration, boot the guest, change the display mode to a 32bit one and then perhaps you can re-enable 3D acceleration.

[mat.tabasko]

Thank you for your fast answer.

I've tried disabling 3D acceleration and booting the guest. The glitches are gone but the boot still hangs.
I've tried disabling 2D acceleration as well (all accelerations disabled) and booting again. Same thing.

find the new logs attached.

[mpack]

Well, you can try booting the guest in safe mode. Unfortunately I'm not sure you can set a graphics mode in safe boot that will still apply in a normal boot. You'll have to experiment. Bear in mind that the objective is to configure to a 32bpp color mode. One thing you might try is to uninstall the VirtualBox Guest Additions in safe mode.

I would also check if disabling the Hyper-v API helps at all.

Ultimately (if all else fails) it ought to be possible to discover a registry location where the Windows guest has stored the current video mode, and edit that to a 32bpp mode.

[mat.tabasko]

Uninstalling the guest additions in safe mode did the trick.

I am now able to boot it normally thank you.

However, when I try to install the guest additions back on the guest the screen goes all black at about half of the installation.
Is there some kind of compatibility issue somewhere?

[mpack]

The only issue will be the same one as before. If you try to reinstall the GAs then Windows will recognize that it already has a cached configuration for the new setup and will choose it by default again. You could only fix this by finding the old config in the registry and deleting it. Hopefully you left 3D acceleration disabled until this is sorted out?

[mat.tabasko]

Altight I understand, i'll try to discrad those configs in my registry.
Yes, 3D acceleration is still disabled.

[MrG247]

Hi All

Unfortunately i still need Win10 for some legacy stuff
Im using Linux Mint 18.3 Cinamon 64bit Host and Win10 64Bit Guest

After hours of testing and searching i found an answer on this site
Make sure in Bios Virtualization is switched on
In VBox - Settings - System - Accelration - Paravirtualisation Interface - Change from Default to KVM

Although Bidirectional is enabled i still cannot Drag/Drop or Copy/paste - So this is my next issue to resolve

[socratis]

In VBox - Settings - System - Accelration - Paravirtualisation Interface - Change from Default to KVM

I'm sorry, but that's completely bogus and useless. A Win* guest will have no use whatsoever if you switch to KVM. KVM is useful only for guests that understand what KVM is, mainly Linux based guests. For Win* guests you need to enable Hyper-V. Which is what Default does in any event.

Although Bidirectional is enabled i still cannot Drag/Drop or Copy/paste - So this is my next issue to resolve

Most probably you didn't install the Guest Additions in your guest. See ch. 4.2 of the user manual.