Restore-certificates flag is been allowed from 3.4.2 manager snapshot to the master manager version. Although the old manager doesn't have any certificates files or directories.
If you still passing this command to the manager, on the snapshot restore stage, you'll get an error message for any command you will pass after the restore.
Steps to reproduce:
Create snapshot of 3.4.2 manager
Restore the snapshot with --restore-certificates flag, on manager with the master version