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I have a Hetzner W2012 R2 Cloud VM, and I updated the VirtIO vioscsi driver on it. Now it only boots into recovery mode and I cannot access the C-drive even from command prompt.

Is there any way to save this VM or is it a goner?
I have no (recent) snapshot of it :(

I can mount the old previous VirtIO ISO, but how can I reinstall the old driver when I have no access to the C-drive?

Update 1:
Am able to get access to the C-drive with drvload vioscsci.inf.
Still trying to figure out how to reinstall the old drivers.

Update 2
I used dism /image:e:\ /add-driver /driver:vioscsi.inf to add the driver but it still won't boot.

Update 3
Startup repair gives error 0x490.

No clue what to do next or how to even troubleshoot why it is not booting.

Update 4

It appears all my system drivers have become unsigned. Disabling driver signature enforcement allowed the system to finally boot.

Do not know why this happened. It appears I will have to do a full reinstall, but at least I got back access to the VM now.

Casper
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  • Yes. I also made sure to uninstall all other versions of vioscsi in case it was still loading something incorrectly. Didn't help either. – Casper Aug 02 '21 at 02:22
  • Change the VM to use Sata/ahci instead of virtio, add an extra disk device with virtio, hopefully windows starts and you can fix the drivers and verify on new disk, shutdown and restore settings. – NiKiZe Aug 02 '21 at 05:10
  • @NiKiZe That might fix it, but as far as I know you can't change the startup parameters on Hetzner Cloud VMs. At least I don't know how to do it. – Casper Aug 02 '21 at 10:26
  • Looks like all my drivers became unsigned. I was able to get into the VM by disabling signature enforcement. – Casper Aug 02 '21 at 16:18
  • Ok. I will post it as an answer if I can't figure out how to fix the signatures. Still trying to figure out that part, but I may throw in the towel soon. – Casper Aug 02 '21 at 16:30

1 Answers1

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1: Disable driver signature enforcement

After much investigation, all system drivers had become unsigned. Cause unknown (possibly drive corruption).

To access the VM I needed to boot without driver signature enforcement.
To do that, first activate the boot menu from Windows Recovery:

bcdedit /set {bootmgr} displaybootmenu yes

Then reboot, press F8 and choose to boot without enforcement.

2: Restore missing security catalogs

For some reason all files in

C:\Windows\System32\catroot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}

...had disappeared. I happened to have a catroot_old folder in System32, so I copied the files from there back into catroot. Using any previous backup would probably have worked too.

This change allowed me to boot normally again.

Casper
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