「cannot unmount /mroot」というメッセージが表示されてONTAP のリバートが失敗する

cluster-01> revert_to 9.10 You are about to revert the system to work with Data ONTAP 9.10 The system will be rebooted immediately after the conversion process completes. Make sure that you have installed Data ONTAP 9.10 onto the boot device, or you will have to run "revert_to" again. Are you sure you want to proceed? [yes/no]? yes debug.nodewatchdog.level: 2 -> 2 error: /etc/netapp_mroot_unmount: cmd_status=1 Error: Revert failed. Cannot unmount /mroot.Unmount all volumes currently mounted under "/mroot/unjunctioned", delete the"/mroot/unjunctioned" directory, then try the command again