The official guidance is not to try to do an in-place upgrade of your Raspberry Pi’s OS. It’s possible, but the recommended route is to write a fresh copy to a fresh microSD card, reinstall any additional apps, and bring across your config files. When we wrote about the Pi-Hole network ad filter earlier this year, we got multiple comments about upgrades going wrong. It’s a free OS that lives on a $5 storage card in a $35 computer. Just buy a new card, write a fresh OS image onto it, and then you can revert by just swapping the old card back in.

Man I love The Reg