Hello , i updated rancher running in k3s cluster using helm upgrade to the new version , rancher is working well all clusters are in rancher server but when i am trying to connect to the cluster using Kubeconfig from rancher it is returning this error :

"2022/08/17 07:59:25 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:26 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:26 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:27 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:28 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:29 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:30 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found
2022/08/17 07:59:32 [ERROR] Failed to handling tunnel request from remote address : response 400: cluster not found
2022/08/17 07:59:32 [ERROR] Failed to handling tunnel request from remote address  response 400: cluster not found"

See if the k3s.yaml file changed?

diff /etc/rancher/k3s/k3s.yaml ~/.kube/config

Yes it seems that there is difference but the clusters are accessible now and the same logs still in rancher , is there any explanation for that ? Thanks!

have you looked at k3s service logs?

journalctl -u k3s.service