Public bug reported: I just reinstalled my RPI3 router from Eoan to Focal but a lot of things about networkd broke. I'm not sure whether they are related or not.
The first thing I noticed was, that I did not get my upstream DNS servers. I use a dispatcher script to extract the information from the json environment variable when my uplink becomes routable. Using a test script to dump the environment I found this: IP6_ADDRS= PWD=/ json={"A": ["ress: 119.224.106.22 (DHCP4)"], "AdministrativeState": "configuring", "Auto negot": ["tion: yes", "peed: 100Mbps", "plex: full", "Port: mii"], "G": ["eway: 119.224.106.21", "DNS: 202.180.64.10", "202.180.64.11", ""], "HW A": ["ress: b8:27:eb:b6:a5:f4 (Raspberry Pi Foundation)", "MTU: 1500 (max: 65535)"], "InterfaceName": "wan", "Jun 20 00:01:49": ["mnus systemd-networkd[534]: wan: netdev ready", "mnus systemd-networkd[534]: wan: Link UP", "mnus systemd-networkd[534]: wan: Gained carrier"], "Jun 20 00:01:50": ["mnus systemd-networkd[534]: wan: Lost carrier"], "Jun 20 00:01:51": ["mnus systemd-networkd[534]: wan: Gained carrier"], "Jun 20 00:01:53": ["mnus systemd-networkd[534]: wan: DHCPv4 address 119.224.106.22/30 via 119.224.106.21"], "Lin": ["File: /usr/lib/systemd/network/99-default.link"], "Networ": ["File: /etc/systemd/network/07-wan.network", "Type: vlan", "tate: routable (configured)", "iver: 802.1Q VLAN Support"], "OperationalState": "routable", "Queue Length (": ["/Rx): 1/1"], "State": "routable (configuring)", "Type": "vlan"} AdministrativeState=configuring IFACE=wan LANG=en_NZ.UTF-8 INVOCATION_ID=384cc7de4e8d45e48ecb2ecf3cb55508 IP_ADDRS= ESSID= ADDR= NOTIFY_SOCKET=/run/systemd/notify SHLVL=1 STATE=routable JOURNAL_STREAM=9:35403 OperationalState=routable PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin networkd_dispatcher_args=--run-startup-triggers Note that the script worked perfectly fine on Eoan. Also when I tried to get the dump above, I ran the following command after installing the test-script: ip link delete wan type vlan; systemctl restart systemd-networkd in order to force networkd to recreate and reconfigure my uplink interface. Doing this resulted in all connectivity with the router being lost (up- and downstream). After a restart, I found the following in the networkd journal indicating that networkd had in fact crashed. Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: Link DOWN Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: Lost carrier Jun 19 23:59:58 tumnus systemd-networkd[539]: wan: DHCP lease lost Jun 19 23:59:58 tumnus systemd[1]: Stopping Network Service... Jun 19 23:59:58 tumnus systemd[1]: systemd-networkd.service: Succeeded. Jun 19 23:59:58 tumnus systemd[1]: Stopped Network Service. Jun 19 23:59:58 tumnus systemd[1]: Starting Network Service... Jun 19 23:59:59 tumnus systemd-networkd[1986]: private: netdev ready Jun 19 23:59:59 tumnus systemd-networkd[1986]: Enumeration completed Jun 19 23:59:59 tumnus systemd[1]: Started Network Service. Jun 19 23:59:59 tumnus systemd-networkd[1986]: private: netdev exists, using existing without changing its parameters Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Main process exited, code=dumped, status=11/SEGV Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Failed with result 'core-dump'. Jun 20 00:00:00 tumnus systemd[1]: systemd-networkd.service: Scheduled restart job, restart counter is at 1. Jun 20 00:00:00 tumnus systemd[1]: Stopped Network Service. Jun 20 00:00:00 tumnus systemd[1]: Starting Network Service... Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: netdev ready Jun 20 00:00:01 tumnus systemd-networkd[2034]: Enumeration completed Jun 20 00:00:01 tumnus systemd[1]: Started Network Service. Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: netdev exists, using existing without changing its parameters Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: Link UP Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: Gained carrier Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: Could not join netdev: Can not enslave a bridge to a bridge. Too many levels of symbolic links Jun 20 00:00:01 tumnus systemd-networkd[2034]: private: Failed Jun 20 00:00:01 tumnus systemd-networkd[2034]: wan: DHCPv4 address 119.224.106.22/30 via 119.224.106.21 Jun 20 00:01:22 tumnus systemd[1]: Stopping Network Service... Jun 20 00:01:22 tumnus systemd-networkd[2034]: wan: DHCP lease lost Jun 20 00:01:22 tumnus systemd[1]: systemd-networkd.service: Succeeded. Jun 20 00:01:22 tumnus systemd[1]: Stopped Network Service. -- Reboot -- However, no crash file had been generated. The system is running systemd 245.4-4ubuntu3.1 and networkd-dispatcher 2.0.1-1. ** Affects: networkd-dispatcher (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1884248 Title: networkd-dispatcher gives corrupted information To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/networkd-dispatcher/+bug/1884248/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs