Information
Windows Server 2019 systems must have Unified Extensible Firmware Interface (UEFI) firmware and be configured to run in UEFI mode, not Legacy BIOS.
GROUP ID:V-205856
RULE ID:SV-205856r991589
UEFI provides additional security features in comparison to legacy BIOS firmware, including Secure Boot. UEFI is required to support additional security features in Windows, including Virtualization Based Security and Credential Guard. Systems with UEFI that are operating in 'Legacy BIOS' mode will not support these security features.
Solution
Configure UEFI firmware to run in 'UEFI' mode, not 'Legacy BIOS' mode.