On Nov 26, I upgraded a Raspberry 4 from buster to bullseye using the standard procedure of edit /etc/apt/sources.list and then apt-get update && apt-get dist-upgrade. Everything went fine, it ran stable for some days and one annoying bug in the openbox window manager occured less often.
On Dec 1, I did aptitude update && aptitude full-upgrade and it found lots of dependency problems. It seems this was mainly caused by changing from gcc-8 to gcc-10 and python 3.7 to python 3.9. I accepte the second suggestion to solve these problems, removing a couple of packages, and the whole upgrade process seemed to work smoothly. But on the following reboot, it showed lots of problems: 1. dhcpcd doesn't reliably get its config, /etc/resolv.conf remains empty and the eth0 interface doesn't get an IP address. 2. Because of 1. NFS mounts fail 3. With restarting dhcpcd this gets fixed but after some time (e.g. hours) dhcpcd fails again repeatedly with dhcpcd[416]: ipv6nd_sendadvertisement: No buffer space available 4. Even when dhcpcd had success and the network is configured, avahi-daemon for no apparent reason eventually changes the interface address. From daemon.log: Dec 4 20:04:50 <host> avahi-daemon[321]: Withdrawing address record for 10.0.0.8 on eth0. Dec 4 20:04:50 <host> connmand[328]: eth0 {del} address 10.0.0.8/24 label eth0 Dec 4 20:04:50 <host> connmand[328]: eth0 {del} route 10.0.0.0 gw 0.0.0.0 scope 253 <LINK> Dec 4 20:04:50 <host> connmand[328]: eth0 {del} route 10.0.0.254 gw 10.0.0.254 scope 0 <UNIVERSE> Dec 4 20:04:50 <host> connmand[328]: eth0 {del} route 0.0.0.0 gw 10.0.0.254 scope 0 <UNIVERSE> Dec 4 20:04:50 <host> dhcpcd[416]: eth0: adding default route Dec 4 20:04:50 <host> dhcpcd[416]: eth0: pid 0 deleted default route Dec 4 20:05:34 <host> avahi-daemon[321]: Registering new address record for 169.254.129.129 on eth0.IPv4. Dec 4 20:05:34 <host> connmand[328]: eth0 {add} address 169.254.129.129/16 label eth0 family 2 Dec 4 20:05:34 <host> connmand[328]: eth0 {add} route 0.0.0.0 gw 0.0.0.0 scope 253 <LINK> 5. Also connmand, which I hadn't in buster, continously logs messages to daemon.log every few seconds: Dec 7 05:48:34 <host> connmand[328]: Skipping server 10.0.0.254 KoD code RATE Dec 7 05:48:43 <host> connmand[328]: Skipping server 10.0.0.1 KoD code RATE Dec 7 05:48:52 <host> connmand[328]: Skipping server 10.0.0.1 KoD code RATE Dec 7 05:48:57 <host> connmand[328]: Skipping server 10.0.0.254 KoD code RATE Dec 7 05:49:06 <host> connmand[328]: Skipping server 10.0.0.1 KoD code RATE 6. The whole network seems unreliable. 7. A couple of changes in the GUI, which I don't care about much at the moment: The Debian logo in the top left of the panel where you get the start menu for app is replaced by a green arrow pointing left. The small icons in the start menus to launch apps are missing The entries in the panel for audio volume, network, and keyboard language are missing. 8. I think there were some other minor issue which I currently don't remember. Now I wonder if there is a chance to get all these things fixed or if a fresh re-install would be easier, faster, and more sucessful. I think, first I should remove connmand, since I don't know what I'd need it for. Steve