When performing an "Unattended Windows installation" with an Answer File, as outlined in Go Fast: Windows 10 and 11 Unattended Installation Answer File Template, you may encounter the following error:

Windows Setup

Windows could not create a partition on disk 0. The error occurred while applying the unattended answer file's <DiskConfiguration> setting. Error code: 0x80042565

This usually means you are using an installation medium with an answer file configured to create a GPT partition table, compatible with a UEFI boot environment, but the machine - while it may be UEFI capable - has booted in Legacy Mode (in which only an MBR partitioning scheme may be installed).

To fix this, reboot and reconfigure your boot settings such that the machine will boot into UEFI or "UEFI first then fallback to Legacy" Mode; alternatively if your BIOS is capable of supporting both modes simultaneously your installation medium may have two boot device entries; one for UEFI mode and one for Legacy. Either ensure the UEFI version of the device is attempted first or use your system's one-off Boot Device Menu (where available) to select the appropriate entry.