Thanks for the help 
Output for above is...
-rw------- 1 admin users 118 Apr 11 21:44 /tmp/bgstatusJ4stCC
As for plugins, ooh, it's been a while. Checking the plugin list it's;
This started a few months ago and I've been keeping my fingers in my ears, hoping it will sort itself out.
The updates always appear to apply fine (the connection lost message comes at the end). But I'd like to get this resolved before I upgrade to OMV7.
Any ideas where I need to start looking? I've had a search about the internet, but I'm still none the wiser.
Illegitimate file owner.
OMV\Exception: Illegitimate file owner. in /usr/share/php/openmediavault/rpc/bgstatusfile.inc:34
Stack trace:
#0 /usr/share/php/openmediavault/rpc/serviceabstract.inc(436): OMV\Rpc\BgStatusFile->__construct('/tmp/bgstatusJ4...')
#1 /usr/share/openmediavault/engined/rpc/exec.inc(99): OMV\Rpc\ServiceAbstract->getBgProcStatus('/tmp/bgstatusJ4...')
#2 [internal function]: Engined\Rpc\Exec->getOutput(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('getOutput', Array, Array)
#5 /usr/sbin/omv-engined(537): OMV\Rpc\Rpc::call('Exec', 'getOutput', Array, Array, 1)
#6 {main}