When setting up a used EX2200 switch we encountered the following error when performing a commit check:

{master:0}[edit]

root# commit check

mgd: unable to execute /usr/sbin/ffp: Bad file descriptor

mgd: unable to execute /usr/sbin/ffp: Bad file descriptor

error: foreign file propagation (ffp) failed

We checked the file system and those binary didn’t exist so we’re assuming that the previous owner messed with the file system and ended up removing some critical stuff.  Probably why they sold the switch.  Simple enough resolution.

Resolution: Reinstall JunOS (in this case we upgraded it)