Manual run Rsync works but UI throws an error and email notification spams my inbox every 2 mins

Hello OMV experts,

I'm using Rsync client + RSync Server (2 x Raspberry 4B) to backup data from one NAS to a backup NAS and everything was working fine for a month or two.

I recently had to rebuild the Raid storage on the backup NAS and I had to delete/recreate all the Rsync jobs (nothing changed on the Rsync server).

However, now when I manually start a RSync Job, I get this error:

Error #0: OMV\ExecException: Failed to execute command 'export
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export
LANG=C.UTF-8; export SHELL=/bin/sh; sudo --shell --non-interactive --
/var/lib/openmediavault/cron.d/rsync-4b0fb2c2-f38e-477f-b182-24f9e2d09215
2>&1' with exit code '1': in
/usr/share/openmediavault/engined/rpc/rsync.inc:263 Stack trace: #0
/usr/share/php/openmediavault/rpc/serviceabstract.inc(588):
Engined\Rpc\Rsync->Engined\Rpc\{closure}('/tmp/bgstatusj0...',
'/tmp/bgoutputVA...') #1 /usr/share/openmediavault/engined/rpc/rsync.inc(267):
OMV\Rpc\ServiceAbstract->execBgProc(Object(Closure)) #2 [internal function]:
Engined\Rpc\Rsync->execute(Array, Array) #3
/usr/share/php/openmediavault/rpc/serviceabstract.inc(123):
call_user_func_array(Array, Array) #4
/usr/share/php/openmediavault/rpc/rpc.inc(86):
OMV\Rpc\ServiceAbstract->callMethod('execute', Array, Array) #5
/usr/sbin/omv-engined(537): OMV\Rpc\Rpc::call('Rsync', 'execute', Array, Array,
1) #6 {main}

The rsync job seems to work fine but I can't see the job output on the UI due to the error above and I'm getting spammed every 2 minutes with an email like this:

Subject: [HOSTNAME] Cron


Please wait, syncing <USERNAME@192.168.x.x::MODULENAME> to </srv/dev-disk-by-uuid-1234567-..-1234560abcd/backups/MODULENAME/> ...


receiving incremental file list


sent 4,197 bytes  received 4,053,016 bytes  62,902.53 bytes/sec total size is 765,478,487,390  speedup is 188,671.01 The synchronisation has completed successfully.

If I disable the option to "Send command output via email" on the Rsync Job everything works and I can see the Rsync progress on the system logs, but I'm wondering what happened since this was working fine before, i.e. I was able to start an Rsync job, see the output on the UI and receive 1 single email when finished with all the output together.

I've already tried to re-create the jobs again without success. I'm using the latest build and I have already installed all the available updates and rebooted the device.

Any thoughts?

[update] I think the emails every 2 minutes are because the job is running continuously as didn't provide any schedule (* * * * *). Now it's set to once per week and the email spamming should stop.

Though, the error above is still an issue.