What does the ‘INVALID FORMAT FOR DATAPACK’ message mean?

The format settings are not compatible with the loaded Datapack/Capture Drive. This could be because the media has been formatted as RAID-1 (check on the Setup->Storage screen) or because the recorder is mistakenly set to record two cameras (Setup->Video->Channels: 2).

Alternatively, if recording ARRIRAW 4:3 @ 48fps with the Onboard M, only the Datapack 512 (orange stripe) and HS Datapack can record this format.