They added a bunch of new functionality for 9.6.2 mostly around being able to provision/netboot OS X devices.
With that being said I do not think that is your problem - I normally see the problem you just stated when one of my PXE services has stopped. It is very common after doing an install of PXE that it doesn't start. I would check that first. Then you could also check to make sure the C:\Program Files (x86)\LANDesk\PXE\System\images\Boot\boot.wim files exist, as this is what it is trying to offer up.
Lastly you may just want to uninstall and re-install the PXE rep. The SP didn't break anything, you likely just got a bad install that time around or a stopped service.
Many thanks for the reply Peter.
I have done some more investigations and find the following.
(All PXE services throughout this exercise have been checked as running.)
Rolled back to a 9.5 SP3 install of LDMS. All PXE services work as expected and I can boot to a template.
Upgraded to 9.6 with NO service pack. No networking was changed at all throughout this testing.
Although the PXE menu has changed, lots of the DOS stuff removed understandably, I could still PXE boot and got my countdown for menu selection.
Installed SP1 for 9.6. No I get now PXE booting. Error message of No boot filename received.
Uninstalled the PXE representative and re-installed it.
Still the same error.
I have now done this 3 times with the same results each time.
How do I fix this? It should just be s simple SP install that should not break PXE services surely?
For us it was fixed by upgrading to the latest agent on the PXE Rep, using Distribution Package "PXE Representative Deployment" to reinstall PXE on the Rep and it worked again.
But we didn't do all the upgrading steps in between to the PXE Rep as you did. Just installed 9.6.2 agent over the 9.5.2 agent.
Already done all of that.
Still no joy.
I have raised a support call now to see what gives.