You're gonna have to give us some info about what you were doing before this appeared. However I see mention of the Master Boot Record (MBR). Macs don't use that partitioning on bootable hard drives. If you are trying to do something on a bootable drive, it needs to be partitioned with the GUID Partition Map scheme.
Ask your TAM if you're running into PI-003061. Composer is broken for capturing OS images since apparently 9.96 when capturing Mac HD and recovery.dmg.
Jamf's suggested solution is to use AutoDMG or remove Recovery HD from the Composer image.
I am currently moving our workflow to AutoDMG. If Jamf doesn't want to support Composer, they should just kill it. If their admin guide is going to say that Composer is supported for capturing base images, IMO, this seems like a pretty large bug.
edit: adding the error I had gotten, little different than yours so maybe it's not same issue