There is a new update available for MDT to address an issue that arises from Windows 10 2004 and the corresponding ADK release:
The issue would only be encountered if you are using non-UEFI devices (physical or VMs). Due to a change in underlying API behaviors, MDT then could not determine if the device was booted using UEFI, so it interpreted the situation as “all devices are UEFI.” There were some workaround posted, but those aren’t recommended as there are multiple places in the MDT process where the “IsUEFI” variable is re-calculated, so you can run into a variety of “gotcha’s.”
This update requires you to manually update the Microsoft.BDD.Utility.dll files in the MDT installation path (so it’s picked up for new deployment shares) as well as in all existing deployment shares. As boot images contain these DLLs, you need to update those too (update them, update WDS, update your media, etc.).
Categories: Microsoft Deployment Toolkit