[German]Users of Windows 10 may experience a nasty surprise when switching to version 1803. Drivers are no longer be loaded and return the error code 39 in the device manager – although all worked before installing the feature update. This is due to Core Isolation (HCVI), which was implemented in all versions of Windows 10 since version 1803 – and can cause the driver error on compatible machines.
The error, that users are facing in Windows 10 V1803 is always the same. The driver suddenly cannot be loaded. Here is the message
Windows cannot load the device driver for this hardware. The driver may be corrupt or missing. (Code 39)
%hs is either not intended to run under Windows or contains an error. Reinstall the program using the original installation media or contact your system administrator or software vendor for assistance. Error status 0x
Within this German MS Answers forum post it has drastic consequences. After installing the feature update lifting the machine to Windows 10 V1803, the Intel(R) HD Graphics 3000 and its drivers no longer works. The Microsoft Basic Display Driver takes over the screen output, but only supports a resolution of 1024 x 768 pixels.
The root cause: Core isolation
Error code 39 indicates an incompatible or damaged driver. But with Windows 10 April Update there is an additional problem, which my German colleague Ingo Böttcher described in his German blog post here. Microsoft has also introduced the so-called core isolation (HVCI) in the home versions of Windows 10 V1803 (previously this was limited to the Device Guard of the Enterprise Edition, see).
HVCI isolates the kernel via the built-in hypervisor (virtualization) to protect it. However, hardware support is needed. As Ingo writes, apart from Virtualbox issues also various drivers have problems with the new HVCI featrue. However, you can control and turn off core isolation on supported machines in the Windows Defender Security Center. Within this article is a screenshot and an explanation how to turn it on – this feature isn#t supported on my test system’s hardware.
A bug prevents disabling HVCI in GUI
In Windows 10 version 1803, however, there is a bug that to my knowledge was not fixed until June 2018. Once an HVCI function has been activated, it can no longer be switched off via the Windows Defender Security Center (see this post). The workaround is to invoke the registry editor via Run as administrator and then navigate to the key:
Then set the DWORD value Enabled to 0 (see also this Microsoft article) and reboot Windows 10. After that HVCI should be disabled and the old drivers (or Virtualbox) should work again.