Quick v5-6.1 sanity check?

[abcd567]

@GlynH

I always have a tough time when it comes to updating this particular Pi as there are a lot of things going on that I am not fully familiar with and the thought of something going wrong and having to troubleshoot causes me to lose sleep!

Raspberry OS / Raspbian updated to Debian 11 "Bullseye"

I have stopped disturbing commissioned/running install for upgrade. Now I have started using a spare microSD Card and a spare Pi. I write latest image to spare microSD card, slip it into spare Pi, install and configure feeders, graphs and any other required software, let it run for a while, and if all is ok, replace old card of main Pi with freshly prepared spare microSD card. This is a very safe way to upgrade.