One fairly common scenario for Operating System Deployment in ConfigMgr is the use of boot media to initiate the OSD process. It’s pretty straightforward: you create the CD/DVD .iso file or bootable USB key, pop it in the system you want to image (or mount the .iso in a virtual environment), and kick off your Task Sequence.
However, in your excitement to get the process set up and begin deploying images everywhere you may encounter a headscratcher right off the bat when you boot to your media and watch the system immediately reboot without showing any available Task Sequences to select. By now you’ve probably figured out the standard practice of hitting F8 to bring up a command prompt and keep the reboot from happening so you can troubleshoot, but the first suspicion experience presents proves false: the boot image has the driver for the NIC and you have an IP address. So, popping open the smsts.log file (located at this point of the process under X:\windows\temp\SMSTSLog) gives you a new error:
Failed to run unattended because there is no mandatory deployment.
Now we know we should be able to select OSD Task Sequences that are deployed as Available, not just those deployed as Required…so what gives?
As it turns out, we got a little click-happy when we created our boot media. On the first screen of the Create Task Sequence Media Wizard, there is a check box to “Allow unattended operating system deployment”. This option is meant to enable more efficient “zero-touch” deployment, bypassing the requirement for any network configuration or selection of optional Task Sequences (though if you have a password set on the boot media it will still be required to continue). Unfortunately, this is commonly likened to the “Enable unknown computer support” option and people therefore check it just in case. However, whereas enabling support for unknown systems doesn’t affect deployment to known systems, enabling unattend deployments actually requires that you have available required deployments…otherwise you end up with the error above.
So, in order to avoid the above error and behavior do not check that box during media creation unless you have a mandatory Task Sequence deployment enabled.