It would be nice ideally if the auto-update had some checking so that dependencies are being met for the upgrade to successfully run, particularly Mono.
If not, at least highlighting it as a warning or stating the minimum requirement on the Status page so that those like me that tend to just let the automation work can come to realise where the root of the problem might be when things act out of the ordinary.
Sure, partially it’s my own doing that it wasn’t the first thing I checked when things started acting weird, but I’d recently also upgraded my QNAP firmware so my initial chosen culprit was there, as opposed to the Sonarr update minimum requirements not being met.