Cannot upgrade a Dkron cluster from 4.0.8 to 4.0.9

[ce-dy]

Describe the bug

Starting from a 22-node Dkron cluster with 3 servers running Dkron 4.0.8, I want to upgrade it to 4.0.9.
The nodes : Linux amd64 CentOS 7

I begin the upgrade process with an agent, as described in upgrade process.
Its 4.0.8 dkron process is stopped with SIGTERM and restarted with the 4.0.9 binary.
All subsequent shell job submissions on this agent fails at leader side with message:
level=error msg="grpc: Error on execution streaming, agent connection was abruptly terminated" error="rpc error: code = Unimplemented desc = unknown service types.Agent" node=leader-node

When I fall back to 4.0.8 on agent node, everything runs fine again.

Thanks for your help.

[ce-dy]

Hello. Still no response. Am I missing something ? Thanks for any help.

[mrhackcz]

I have the same problem. Related to #1887

Server 1:
There is one public IP and one IP from wireguard. When I change bind-addr to bind-addr: "0.0.0.0:8946" dKron starts.

Server 2:
There is only one public IP. When I change bind-addr to bind-addr: "0.0.0.0:8946" dKron fails with:

INFO[2026-02-24T16:57:56+01:00] agent: Dkron agent starting node=server2.cz
ERRO[2026-02-24T16:57:56+01:00] Failed to create memberlist: failed to get final advertise address: failed to parse advertise address "<nil>"  node=server2.cz
Error: agent: Can not setup serf, Failed to create memberlist: failed to get final advertise address: failed to parse advertise address "<nil>"
agent: Can not setup serf, Failed to create memberlist: failed to get final advertise address: failed to parse advertise address "<nil>"

[enzo-pauvy]

Upgraded from 4.0.4 to 4.0.9 recently, I had to add the advertise-addr attribute in my dkron.yml config.

[vcastellm]

Feel free to reopen in case the solution from @enzo-pauvy doesn't work