During a DVR upgrade via the web interface, all the ffprobe processes associated with the ongoing recordings are left and become zombies.
If somebody would like to poke around the messagepack of the interrupted job. The zombie PIDs are 2412978 2442169 2442200 and one of them is probably associated with the job
bbolt get recorder.db jobs 1771257600-131
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Netdata confirms, the number of zombies jumps after clicking 'upgrade' in the 'waiting to upgrade' state:
