Windows 10 20H2 and 2004 upgrades blocked over Intel Thunderbolt 'DMA violation'

Microsoft says Intel's Thunderbolt interface has a compatibility problem with the two latest versions of Windows 10.
Written by Liam Tung, Contributing Writer

Microsoft has warned Windows 10 users that they might be blocked from upgrading to Windows 10 versions 2004 or 20H2 due to a compatibility issue with Intel's Thunderbolt NVMe SSD. 

Whenever Microsoft releases a new feature update – even minor ones, like Windows 10 20H2, which is basically the same as version 2004 – hardware drivers invariably run into compatibility issues. 

This time, Intel and Microsoft have found that a compatibility issue with these two versions of Windows 10 causes a nasty blue-screen error when plugging in an external NVMe SSD via Thunderbolt.

SEE: Windows 10 Start menu hacks (TechRepublic Premium)

Microsoft warns that on either version of Windows 10 users might see a blue-screen error stating: 'DRIVER_VERIFIER_DMA_VIOLATION (e6) An illegal DMA operation was attempted by a driver being verified.'

DMA refers to Direct Memory Access, which Thunderbolt has when plugged in, allowing a device to transfer data to and from memory without using the processor. 

Microsoft says in a new support note explaining the compatibility hold that Windows 10 devices affected by this error will have at least one Thunderbolt port.

"To safeguard your update experience, we have applied a compatibility hold on Windows 10 devices with affected drivers or firmware from being offered Windows 10, version 2004 or Windows 10, version 20H2," it says. 

According to Microsoft's Windows hardware developer notes, DRIVER_VERIFIER_DMA_VIOLATION (e6) relates to Driver Verifier DMA Verification, which monitors the use of DMA.   

Microsoft and Intel are working on a fix that should arrive in an upcoming release, Microsoft said. 

SEE: Windows 10: Microsoft details workaround for 'Reset This PC' failures in 2004 update

It's not clear why the error has emerged for Windows 10 version 2004 only now. According to a user report on Microsoft's answers page, one of the organization's Lenovo P53 Notebooks suddenly hit the blue-screen DMA error on September 16.  

"One of our Lenovo P53 Notebooks threw this blue screen today, out of nowhere (the user was typing in notepad). It is not reproducible," the user wrote, adding that the driver verifier was disabled. The notebook, running Windows 10 2004, was connected to a Lenovo ThinkPad Thunderbolt 3 Dock Gen 2. 

Security concerns over Thunderbolt's DMA have prevented Microsoft from supporting Thunderbolt on its Surface PCs. However, in Windows 10 1803, Microsoft implemented kernel Direct Memory Access (KDP) protection for Windows 10 OEM laptops with Thunderbolt 3 to protect against attacks requiring physical access.

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