The WinPE 2.x path to the BCD file needed to boot, is saved and retrieved by the same function based on a flag. The input information to the routine is a working copy of the incoming packet from the client that is booting. If the DS primary lookup keys include either MAC or UUID then no problem is seen. However, if Serial Number is the only primary lookup key used, then the routine does not look for this extra information in the working packet. The routine only looks for the standard DHCP packet header information that can include both the MAC and GUID. (We modify the GUID into the UUID form of the value.) By not having the single DS primary lookup mask value then the BCD path data is put into a bit bucket because no match is made to any available Client Record stored by the PXE Server.

This also happens when the client is known to DS and had been doing Automation jobs and then was deleted from the DS database. During the delete cycle by DS, a message is sent to the PXE Server to remove the DS known information from the PXE Server in memory Client Record list. One piece of information was not removed and this was the DS Primary Lookup key mask. Even though the client was no longer known to DS the client was set to the unknown state and would boot to initial deploy. A match to the client record was prevented because the DS mask was used and an exact match had to be made. This caused the client (when booting WinPE 2.x) to fail by not finding the required path to the BCD file.

It is also possible that the pxeboot.bcd file was not being copied into the \Images\MenuOptionxxx\x86PC directory.  This can be caused by a corrupt Bootworks installation which fails to copy this file when regenerating WinPE images.  

Another possible cause can be that the files at the \WAIK\Tools\PETools\x86\boot directory are 0 byte files.  This includes the bcd, boot.sdi, bootfix.bin and the etfsboot.com.  If these files are 0 byte files, then the WinPE 2.1 installation did not function correctly.