Can't boot computer after enabling Client Hyper-V

Question

I have a CyberPowerPC with an Intel chip that supports virtualization. I noticed that VirtualBox is somewhat sluggish with GUI virtual machines so I decided to enable Client Hyper-V to see if that worked better. I followed the powershell instructions here. After reboot my computer wouldn't get past the three dot wheel before going to a black screen and rebooting.

I subsequently found a recovery boot screen that allowed me to boot into safe mode. I used safe mode's power shell to disable Client Hyper-V. Upon restart the system went back to normal mode without my re-enabling it (I guess that's default behavior?) and still wouldn't boot.

I checked to make sure virtualization was enabled in UEFI and it was. I tried disabling it. Still no good.

After attempting to get back into Safe Mode the computer went straight to a Restart Screen and now I'm back in normal mode.

Please Help. I don't even know how to consistently get into safe mode. I can't even reach a login screen unless it's in safe mode and I don't know how to consistently reach safe mode. My boss is in the other room and doesn't' know about the trouble I'm having. My stomach is in my throat. Panic

Right now I'm in safe mode attempting a data backup.

UPDATE: More data: Processor Intel Core i7-3820 @3.60 GHZ, 16 GB Ram, 64-bit Windows 10 Pro

Problem: Enabled Client Hyper-V via PowerShell and rebooted when prompted. Boot process reaches dot circle loading screen before cutting to black and auto-rebooting in reboot loop.

Troubleshooting Steps taken: 1) Booted into safe mode, disabled Client Hyper-V via PowerShell. Rebooted when prompted. Booted into normal mode. Result: Still see dot circle loading screen cut to black auto-reboot loop.

2) Disabled virtualization in UEFI. Result: Same

3) Re-enabled virtualization in UEFI. Result: Same

4) Booted into safe mode to backup all data. Hyper-V appears unchecked in 'Turn Windows Features on/off' menu.

UPDATE2: I noticed in msconfig.exe that there are several services labeled Hyper-V. I unchecked all of them and performed a normal boot. Result: same.

Answer 1

Did you ever sort this out? I just ran into the issue while trying to run Docker in Windows 10 x64.

It's definitely being caused by Hyper-V, but I haven't discovered exactly why or how to fix it yet. What I have found though in the meantime to still be able to boot into Windows (not just Safe Mode, and obviously without Hyper-V being usable once booted) is to toggle off Hyper-V via your BCD file.

You have to be able to get to a command-line though. What I've been doing is wait for startup repair to fail, then boot into Safe Mode. From there I open up an elevated (Admin) Command-line and type this:

BCDedit /set hypervisorlaunchtype Off

Then reboot.

If you have more than 1 item in your BCD you might need to specify which item to turn hypervisor off on. You can view all BCD items just by typing:

BCDedit

And to specify the item to alter, just add in its ID:

BCDedit /set {<long string of numbers here>} hypervisorlaunchtype Off

NOTE: When installing Hyper-V, it apparently automatically sets that flag to "Auto" (on) in your BCD, which causes the BSOD/Boot Repair Loop. Once you get the problem sorted out, you'll need to set that flag back to "Auto" to use Hyper-V again. I always make 2 boot choices in my BCD; one with Hyper-V enabled, one with it disabled. Then I select the one I want as needed.

Answer 2

Try to restore Windows to its state before, with this procedure.

1. Boot into recovery mode or try to boot three times to trigger automatic repair
2. Click on Advanced Startup
3. Click on Troubleshoot
4. Click on Advanced options
5. Click on System Restore
6. Click Next
7. Select the most recent known working restore point
8. (Optional) Click the Scan for affected programs button to see the applications that will be removed if they're installed after the restore point was created
9. Click Close
10. Click Next
11. Click Finish
12. Reboot.

Answer 3

This worked for me once I was able to get back into Windows:

1. Open "Window Security"

2. Open "App & Browser control"

3. Click "Exploit protection settings" at the bottom

4. Switch to "Program settings" tab

5. Locate "vmcompute.exe" in the list and expand it

6. Click "Edit"

7. Scroll down to "Code flow guard (CFG)" and uncheck "Override system settings"

8. Reboot

Answer 4

The cause of this problem is that Windows 10 does not add the "hypervisorlaunchtype auto" entry to the BCD file when Hyper-V is switched on. That is why it will not boot. The moral of the story is: add this entry to BCDEdit BEFORE switching on Hyper-V. If you haven't (and I hadn't!) you have an unbootable Windows. The workaround is to boot up with a WinPE bootable CD (you have made one and tested it, I hope), then use Diskpart to navigate to the disk and relevant partition (the EFI partition), select this partition, assign it a letter (suppose it was J:), exit, then run BCDEdit and point it to the BCD file J:\EFI\Microsoft\boot\BCD in order to add the missing entry. The command would be

bcdedit /store J:\EFI\Microsoft\boot\BCD /set {default} hypervisorlaunchtype auto The response should be "successful". Then reboot your system. You can then use BCDEdit online in a command prompt (bcdedit /enum) to list the file; the {default} system entry should now carry the parameter hypervisorlaunchtype auto. That's it. Now Microsoft - fix this please in Windows 10!

Answer 5

However this is not the whole answer. Windows 10 may not boot if Hyper-V is enabled even with the required BCD entry. You may have to set the BCD hypervisorlaunchtype entry to OFF to keep Hyper-V switched off and use a reliable alternative such as Oracle's VirtualBox.

Answer 6

It's actually worse than that. IN Win 10 1909, even if the BCD entry is AUTO and Hyper-V is ON, system will fail to boot. The only reliable way to run Win 10 1909 is to leave Hyper-V OFF and have no entry in BCD, or the entry "hypervisorlaunchtype Off" (it may be deleted anyway).

Answer 7

Strange. I had the same problem with the circling dots for a day. But then I did some OSX updates in Sierra, and then it booted back into Windows 10 1909 no problem.

Answer 8

In some AMD products there is a problem with SVM in BIOS, which causes a collision between the BCDedit function "hypervisorlaunchtype".

Algorithm for troubleshooting the issue:

1. Reboot to BIOS and disable SVM function.
2. Reboot to Windows.
3. If success then check the "gcdedit /set hypervisorlaunchtype off" so if its off then done. If its auto then change to off.
4. If reboot to Windows did not succeed then reboot to repair mode.
5. Restore windows latest snapshot. If success then go to step 3.
6. Done.

I figured it out when I tried to run those scenarios:

1. SVM off + hypervisorlaunchtype off
2. SVM off + hypervisorlaunchtype auto
3. SVM on + hypervisorlaunchtype off
4. SVM on + hypervisorlaunchtype auto

Now Im on the 3 option and other apps run alright.

To solve the issue: A downgrade of the BIOS or changing to other compatible product may solve the issue.