This occurs when booting to PXE automation and the following error is received:
PXEPreZero: Invalid PXE Server list format PXE-MOF: Exiting Intel Boot agent.
GSS 3.3.x
DS 8.x
Option 60 (PXE forced mode) is set up on the DHCP, but the scope options are set incorrectly.
Make sure the scope options for option 60 are set correctly using this KB article: Setting up Vendor-specific PXE Forced Mode