OK,
firstly, as you mentioned, moving from Stretch to Buster via updating was very much not recommended; which is very irritating when it means you have to work out what the hell you have added/changed so you can replicate it. Surely there must be some way of finding that stuff out and auto-generating some kind of script?

Secondly, the crash dump shows you are running a late 2018 vm so I strongly recommend updating that. I faintly recall having a fatal crash during update last summer(ish) but I changed the vm and haven't seen anything since.



tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Useful Latin Phrases:- Nihil curo de ista tua stulta superstitione = I'm not interested in your dopey religious cult.