Upgrading Raspbian from Buster to Bullseye

To upgrade from Raspbian Buster to Raspbian Bullseye, I followed the procedure described in the RaspberryPi Forum: https://forums.raspberrypi.com/viewtopic.php?t=323279 but since I do not use the graphic GUI I skipped editing the /boot/config.txt file to specify the display driver.

After a reboot, the system was not reachable via SSH. A ping to it's IP address failed, too. I connected a screen and a keyboard and found out that networking.service was unable to start ("failed to start raise network interfaces"). ifup could not find the device "eth0". Instead, networkctl and ìfconfig -a showed me a device named "enx"followed by the MAC address. Following this article https://forums.raspberrypi.com/viewtopic.php?t=298012#p1940960 I added net.ifnames=0 biosdevname=0 to \boot\cmdline.txt and after a reboot eth0 was back again. The solution somehow interferes with predictable network names, as this article describes https://forums.raspberrypi.com/viewtopic.php?t=299352. But it is working for me. Now it was time for an intermediate backup.

The upgrade process leaves some packages marked as "auto" and since there are no dependencies apt proposes to autoremove them. If you do this the Pi will not to boot any more. So I marked the package "raspberrypi-sys-mods" as "manual

sudo apt-mark manual raspberrypi-sys-mods

and also sone other packages I consider useful: bsdmainutils, device-tree-compiler, dh-python, dos2unix, fdisk, usb.ids, liblzo2-2, rpi-eeprom-images. After that I was able to run the autoremove command and the Pi booted normally afterwards.

To make smarthomeNG run, some Python packages need to be re-installed and then smarthomeNG is started:

sudo apt-get -y install dialog python3 python3-dev python3-setuptools unzip git-core build-essential python3-pip
python3 bin/smarthome.py

smarthomeNG then installs additional Python packages and restarts.

To make sure the PHP packages are up-to-date for the smartVISU server, I tried to re-install the packages:

sudo apt-get install libawl-php php-curl php php-json php-xml php-mbstring

but all were already up to date.