Microsoft Explains Why Windows 10 is Crashing on Lenovo Laptops

Microsoft has acknowledged that changes introduced in recent Windows 10 2004 updates cause crashes on Lenovo ThinkPad laptops and has offered a workaround.

After users installed the July’s Windows 10 2004 KB4568831 update, Lenovo ThinkPad users found that their laptops would crash with “SYSTEM_THREAD_EXCEPTION_NOT_HANDLED” (in the Stop error message screen) and “0xc0000005 Access Denied” errors.

Soon after, Lenovo warned that ThinkPad models from 2019 and 2020 with Virtualization enabled in the “Enhanced Windows Biometric Security” setting, could encounter crashes and other bugs.

These crashes could occur when the following activity was performed:

• Blue Screen of Death (BSoD) when booting
• Blue Screen of Death (BSoD) when starting Lenovo Vantage
• Blue Screen of Death (BSoD) when running Windows Defender Scan
• Can’t login by Face with Windows Hello
• Errors in Device Manager related to Intel Management Engine
• Errors in Device Manager related to IR Camera

In a support bulletin released this week, Microsoft states that the KB4568831 updates, and those that came later, restrict how processes can access certain regions of memory known as PCI Device Configuration Space.

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If a process attempts to access a  PCI Device Configuration Space in an unsupported manner, it will cause Windows 10 to crash with a Stop error.

“Windows devices that receive the July 31, 2020—KB4568831 (OS Build 19041.423) Preview or later updates restrict how processes can access peripheral component interconnect (PCI) device configuration space if a Secure Devices (SDEV) ACPI table is present and Virtualization-based Security (VBS) is running. Processes that have to access PCI device configuration space must use officially supported mechanisms.”

“The SDEV table defines secure hardware devices in ACPI. VBS is enabled on a system if security features that use virtualization are enabled. Some examples of these features are Hypervisor Code Integrity or Windows Defender Credential Guard.”

“The new restrictions are designed to prevent malicious processes from modifying the configuration space of secure devices. Device drivers or other system processes must not try to manipulate the configuration space of any PCI devices, except by using the Microsoft-provided bus interfaces or IRPs. If a process tries to access PCI configuration space in an unsupported manner (such as by parsing MCFG table and mapping configuration space to virtual memory), Windows denies access to the process and generates a Stop error,” Microsoft explains in a support bulletin.

Microsoft Offers a Workaround Until a Fix is Released

Microsoft states that they are currently working on a fix with Lenovo to prevent these crashes in Windows 10 2004.

For those who do not want to wait for the fix, Microsoft has offered a temporary workaround of disabling the ‘Enhanced Windows Biometric Security’ security feature in the laptop’s UEFI configuration.

To disable this feature, boot into the laptop’s UEFI setup screen, and under the Security > Virtualization menu, check the Enhanced Windows Biometric Security setting status.

If it is enabled, you can sacrifice some security on the laptop to prevent the crashes until a fix is released.

“To temporarily mitigate this problem, edit the device UEFI configuration (in the Security > Virtualization section) to disable Enhanced Windows Biometric Security. This change disables the restrictions that are enabled by the SDEV table and VBS,” Microsoft explains.

Microsoft has not stated when their fix will be ready, but will likely require software, and possibly firmware, updates from Lenovo first.

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