openmediavault-backup 3.9 fails with message: Failed to execute command

Failed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; omv-mkconf backup 2>&1': sending incremental file list home/deluge-daemon/.config/deluge/state/ home/deluge-daemon/.config/deluge/state/torrents.fastresume home/deluge-daemon/.config/deluge/state/torrents.state var/cache/openmediavault/archives/ var/cache/openmediavault/archives/Packages var/lib/unifi/db/ace.0 var/lib/unifi/db/ace_stat.0 var/lib/unifi/db/ace_stat.ns var/opt/sickbeard/Logs/sickrage.log sent 55,049,393 bytes received 8,846 bytes 2,685,767.76 bytes/sec total size is 3,194,546,655 speedup is 58.02 Root drive: /dev/mmcblk0p dd: failed to open '/dev/mmcblk0p' : No such file or directory

Show details:

Error #0: exception 'OMV\ExecException' with message 'Failed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; omv-mkconf backup 2>&1': sending incremental file list home/deluge-daemon/.config/deluge/state/ home/deluge-daemon/.config/deluge/state/torrents.fastresume home/deluge-daemon/.config/deluge/state/torrents.state var/cache/openmediavault/archives/ var/cache/openmediavault/archives/Packages var/lib/unifi/db/ace.0 var/lib/unifi/db/ace_stat.0 var/lib/unifi/db/ace_stat.ns var/opt/sickbeard/Logs/sickrage.log sent 55,049,393 bytes received 8,846 bytes 2,685,767.76 bytes/sec total size is 3,194,546,655 speedup is 58.02 Root drive: /dev/mmcblk0p dd: failed to open '/dev/mmcblk0p' : No such file or directory' in /usr/share/openmediavault/engined/rpc/backup.inc:72 Stack trace: #0 /usr/share/php/openmediavault/rpc/serviceabstract.inc(528): OMVRpcServiceBackup->{closure}('/tmp/bgstatusyK...', '/tmp/bgoutputbG...') #1 /usr/share/openmediavault/engined/rpc/backup.inc(75): OMV\Rpc\ServiceAbstract->execBgProc(Object(Closure)) #2 [internal function]: OMVRpcServiceBackup->doBackup(NULL, Array) #3 /usr/share/php/openmediavault/rpc/serviceabstract.inc(124): call_user_func_array(Array, Array) #4 /usr/share/php/openmediavault/rpc/rpc.inc(86): OMV\Rpc\ServiceAbstract->callMethod('doBackup', NULL, Array) #5 /usr/sbin/omv-engined(536): OMV\Rpc\Rpc::call('Backup', 'doBackup', NULL, Array, 1) #6 {main}

/dev/mmcblk0p1: UUID="cd9bebc4-a674-45e5-a7fa-9f7c5c466a84" TYPE="ext4" PARTUUID="844ddb18-01"
/dev/sda: UUID="ITL1fN-eKjx-v53J-49pM-C3Gp-XKCZ-hAToQf" TYPE="LVM2_member"
/dev/mapper/Helios4VolumeGroup-Helios4LogicalVolume: LABEL="Helios4FS" UUID="d6997057-e4a0-4e92-95bf-0e04e9f3eeb0" TYPE="ext4"
/dev/zram0: UUID="2d0ff208-093c-4094-8c6c-02835cce65ce" TYPE="swap"
/dev/zram1: UUID="1c033475-2089-4e25-b40c-6c8c791e18f5" TYPE="swap"
/dev/mmcblk0: PTUUID="844ddb18" PTTYPE="dos"
/dev/mmcblk0p2: PARTUUID="844ddb18-02"