virtualbox.org

VirtualBox 5.2.6 was unable to start after installation KB4571756 Windows 10 Update.
None of my VMs want to start via command line as well.
It displays the message like "This App cannot be launched because of security reasons".
Removing update solved the problem.
I've paused Win updates for 7 days.
Windows 10 Pro 2004 Build 19041.388

Does somebody face with the issue?

Hola ambicrys, a mi me pasó lo mismo. Desinstalando la actualización KB4571756 volvió a funcionar el VirtualBox. Hay un artículo de microsoft que dice que deshabilitando Hyper-V debería funcionar, pero no lo pude testear todavía.

If kinui666's information is correct, disabling Hyper-V can be done by this process:

1. Shut down all programs. You will have to reboot your host.

2. Look into I have a 64bit host, but can't install 64bit guests, 2nd post, points 2 & 3 and ensure that none of these things are running.

3. Find the Command Prompt icon, right click it and choose Run As Administrator.

4. Enter this command:

bcdedit /set hypervisorlaunchtype off

5. Enter this command:

shutdown -s -t 2

6. When the computer turns off, unplug it for 20 seconds. Then plug it in again and boot up Windows 10.

Web-searching "KB4571756 Windows 10 Update" leads to this: https://www.windowslatest.com/2020/09/0 ... ndows%2010. which may indicate that WSL2 and Hyper-V are running and having issues over the update.

Virtualbox is being worked on to run under Hyper-V, but the path is not complete yet.

I had problem starting vms after the recent Tuesday update I did last night
for VB 5.1.xx and 5.2.xx.
went for VB 6.1.12r139181(qt5.6.2) and voila all my vms was able to start

BTW: I like the features look for the Vb 6.1.12r139181. I should have updated by in July. would have same me a lot of work with vm moving....

scottgus1 wrote:If kinui666's information is correct, disabling Hyper-V can be done by this process: ...

Thank you for a quick response!
But none of Hyper-V components is installed in my Windows and therefore could not interfere with VirtualBox, I suppose...
I will check your suggestions next time the win update will be installed again.
Info from mpack from your link is very useful, thanks!

Mpack's link will show you a lot more stuff that uses Hyper-V besides that Hyper-V checkbox. Thus the "bcdedit" silver-bullet command.

We are having the same issues
VirtualBox 5.2.20 was unable to start after installation KB4571756 Windows 10 Update.
None of VMs want to start via command line as well.
It displays the message like "This App cannot be launched because of security reasons".
Removing update solved the problem. Also bumping the version to 5.2.22/6.1.14 fixed the issue.
Updating the VirtualBox is not currently an option thus looking for other option.
Windows 10 Pro 2004 Build 19041.388

That update has some security fixes. I would think that the best option would be update to 19041.508 (that is what KB4571756 does) and also update the VirtualBox to 6.1.14 . Version 5.2.6 is pretty old. If you really want to stay on 5.2.6, don't update the host OS.

Apparently, Microsoft decided to disable older versions up to 5.2.21.

Best would be to switch to new version, but if that is not possible you can change behavior
of Program Compatibility Assistant using Compatibility Administrator (part of Windows ADK).

Install Windows ADK (Assessment and Deployment Kit).
During installation you need to select Application Compatibility Tools,
and if you do not need other tools from ADK deselect everything else to save download time and space.
Run Compatibility Administrator and in left side panel expand System Database, expand Applications, find and select VirtualBox.
On right side panel find entries with "HARDBLOCK" and disable them (Rightclick, Disable Entry).
That solved problem for me.

That solved the problem for us.
This gives us time to follow the upgrade path while current deployment goes on.
Thanks