Sorry I did not update this earlier, but it turned out to be that the name of the pod was too long in my case. I shortened it from "docker-builder" to "builder" and things worked again. 

I've seen this when one of the containers in the pod (other than the jnlp one) fails to start. The plugin sees the pod has errored and deletes the agent entry in the jenkins master side (or doesn't even get to create it) , then the jnlp container tries to connect and fails with 'Unknown client name'

i'm seeing this same issue although w/ slightly different behavior. the container connects and is able to successfully talk to jenkins and run the build but then seems to error out afterwards.

it's almost like jenkins deletes the slave but the slave is still expecting to be able to talk back to jenkins.

i'll post logs from the container in a second.

i should also note that only the jnlp container is involved in my setup.

a downgrade to version 0.11 of the plugin seems to resolve this issue.

jgangemi you are probably experiencing JENKINS-45910

Just confirming that we saw this behaviour too, and csanchez suggestion, that another failing container triggers this, was correct

We are having a very similar problem too. What we found out is that, when there are multiple builds in the queue with different labels, the plugin will try to provision a few slaves at the same time ( due to the non-blocking nature of provision method in KubernetesCloud class )

For example, If I have 5 builds waiting in the queue, it will try to provision 5 slaves simultaneously, even my container cap is set to 3. Exceeding the cap is a minor problem though. The real problem is, these 5 slaves will soon be dead because of this "None of the protocols were accepted" error.

I ended up adding a sleep in the provision method: https://github.com/faraway/kubernetes-plugin/commit/364abb99ccb6defc539b90882d1854305e39d01a and had a custom build(So that it only provision one slave at a time). And things started to working great for us for the past few weeks. 

Despite of this lame fix, my question is wether this is something I did wrong ( Maybe I should use same label for all the repos and all the builds ? ). If this suppose to work then I'm interested to fix it, any directions or instructions from the maintainers will really help me.

My apologies that it seems I'm hijacking this ticket, it's just the errors look exactly the same. Please advise if I should better create a new ticket. 

you should open a new ticket if you see that concurrent provisioning is failing, but for that you need to provide the logs https://github.com/jenkinsci/kubernetes-plugin#debugging to be able to diagnose the issue

fyi, i saw this issue when my jenkins hosts' (my mac) IP changed. I updated kubernetes cloud config's jenkins host and tunnel host ip and that fixed it for me. It also happens if IPs are pointing to some other jenkins host from which you haven't submitted original job.

FYI.

For me, no issue in following version.

Jenkins: 2.289.2-lts

kubernetes-plugin:1.30.0