This error can cause confusion... including thoughts of having to change UEFI machines back to BIOS to enable ASR (not the most pleasant of tasks!). UEFI shouldn't really be mentioned as it is supported. Secure Boot is a setting within the UEFI bios menu; having this enabled is not supported with ASR.
For VMware / physical machines:
UEFI + Secure Boot Enabled = not supported
UEFI + Secure boot Disabled = supported
If you are using 'Device Guard' on servers then Secure Boot is required.