Hi,
We've had a SCCM 2012r2 OSD environment set up for a year and a half now, and it's been working pretty much flawlessly for both UEFI and legacy BIOS computers. Starting early last week we started encountering problems with some of our laptops where after the image is applied, the next reboot comes up to a black screen stating:
"Remove disks or other media. Press any key to restart."
after pressing any key, it comes up to another black screen stating:
"No boot device found. Press any key to reboot the machine. "
additional restarts show the same (second) message.
This appears to be caused when the 350MB Bitlocker partition (configured to not receive a drive letter - and never had a drive letter before now) is assigned the drive letter C, and the OS partition where the userstate USMT folder resides is assigned the drive letter D. Watching the task sequence I can tell when a computer will have this problem because on the Apply Operating System step, it's applying to volume D:\ instead of C:\
A workaround is to boot into a windows to go USB drive, mount the internal drive, and remove the drive letter from the bitlocker partition, and restart without windows to go. SCCM then picks up right where it left off. With several hundred computers to refresh from 7 to 8.1 this is not an acceptable solution.
after testing it on different models we found that it only occurs when the BIOS is set to legacy mode and the task sequence skips the format/partition disk steps - as in refresh scenarios with user data. most of our laptops have a UEFI option, but even if we could change it that would require backing up user data manually, and not all of our laptops have this option, so we're looking to find the root cause, whatever changed that broke our task sequence or WinPE. Unfortunately, it appears that no changes were made in the past 2 months to either the boot image or the task sequence.
Our PXE boot has no problem with legacy BIOS machines as it wipes the drive and reformats the partitions (350MB for bitlocker, do not assign drive letter checked, and the rest for the OS), it's only when initiated via software center that it assigns C:\ to the bitlocker partition. It did not have a drive letter assigned when the task sequence was run, it seems to assign it after it boots into PE.
UEFI-configured devices still work flawlessly, but they account for a relatively small percentage of our client machines. Just worth noting that Legacy BIOS computers used to work flawlessly too up until last week.