Hello Hansen, Joshua,
The Secure Boot Violation error during PXE boot indicates that the bootloader files provided by your PXE system do not meet the Secure Boot requirements of the UEFI on your clients. The fact that devices with pre-installed Windows or via USB boot without issue shows that the local bootloader signatures are valid, while the PXE-provided files are either unsigned or come with an older certificate. In many environments outside the US, PXE works because Secure Boot is either disabled there or the PXE servers use updated Microsoft UEFI CA 2023 signatures.
You should check whether your PXE server is providing the latest bootloader files (bootx64.efi, wdsmgfw.efi) from Windows Deployment Services or the latest ADK/WinPE package. If these files are older or not signed with the new Secure Boot certificates, the clients' UEFI will block booting. Comparing them with the version on a working USB installation medium will help identify the differences. It's also crucial that the clients' NVRAM database contains the Microsoft Windows Production PCA 2011 and the Windows UEFI CA 2023, as only bootloaders with these signatures are accepted.
In short, the problem isn't with the clients, but with the PXE boot files, which don't comply with the current Secure Boot requirements. Update the bootloader files on the PXE server with the latest versions from the Windows ADK/Deployment Tools, and the Secure Boot Violation error should disappear.
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Thank you,
HL.