Description: TFTP Download failed.The PXE Rep does not have the Boot folder under images, so it appears that the PXE rep is not getting installed correctly.
Old core server is listed as a preferred server in the new core. The Preferredserver.dat files are not getting deleted from the PXE Rep machine, so the when the PXE install requests the OSDRep.msi, it gets it from the preferredserver.dat and pulls the msi from the old core, thus installing an incompatible PXE rep for WINPE 2.5.
Remove the 8.7 or 8.8 core information from the preferred server list on the 9.0 core. (This is in Configure > Preferred Servers)
Deleted the preferredserver.dat file from the landesk\ldclient\sdmcache folder on the PXE Rep machine (This file only gets updated every hour or so if the file already exists)