Error testing connection.KubernetesClientException.An error has occurred. when trying to connect with kubernetes cluster

[Anirudh-alb]

Current setup

(not proficient in kuberneres)
Host machine is MacOs Sequoia M4 pro
minikube cluster ws started with
minikube start --cpus=4 --memory=6100
A minikube cluster, Jenkins runs inside this minikube cluster as a deployment & it is running fine.
For service a NodePort was created followed by a
minikube service jenkins-service -n devops-tools --url
command to get a url to access jenkins from host machine.
Next a user is created , then Manage Jenkins -> Clouds -> Install plugin -> Kubernetes is installed -> Create a new cloud ->
Here is the cloud config

name: Kubernetes
Kubernetes URL 
https://kubernetes.default.svc.cluster.local:443

Kubernetes Namespace
devops-tools

Disable https certificate check
Enabled

Jenkins URL
http://jenkins-service.devops-tools.svc.cluster.local:8080

Jenkins Tunnel
http://jenkins-service.devops-tools.svc.cluster.local:50000

other stuff is kept default
for why these values are chosen is i used claude for debugging and these values seemed correct to me

Some logs that may help

kubectl describe pod -n devops-tools jenkins-8cc6659c6-p27b8

Name:             jenkins-8cc6659c6-p27b8
Namespace:        devops-tools
Priority:         0
Service Account:  jenkins-admin
Node:             minikube/192.168.49.2
Start Time:       Fri, 27 Jun 2025 11:01:31 +0530
Labels:           app=jenkins-server
                  pod-template-hash=8cc6659c6
Annotations:      <none>
Status:           Running
IP:               10.244.0.9
IPs:
  IP:           10.244.0.9
Controlled By:  ReplicaSet/jenkins-8cc6659c6
Init Containers:
  volume-mount-hack:
    Container ID:  docker://75b76c203eaaa6ca71ffe2e81ab85458b0042e136547f900537a799583fe00cb
    Image:         busybox
    Image ID:      docker-pullable://busybox@sha256:f85340bf132ae937d2c2a763b8335c9bab35d6e8293f70f606b9c6178d84f42b
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      chown -R 1000:1000 /var/jenkins_home
    State:          Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Fri, 27 Jun 2025 11:01:35 +0530
      Finished:     Fri, 27 Jun 2025 11:01:35 +0530
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/jenkins_home from jenkins-data (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-csncj (ro)
Containers:
  jenkins:
    Container ID:   docker://f72287341f7af7687119029a98448403fed364c581281ff30874df3aa1a343a6
    Image:          jenkins/jenkins:2.504.2-lts-jdk21
    Image ID:       docker-pullable://jenkins/jenkins@sha256:2abbd073f06850c3c962eedaa10e7aa21c517db1e582ad8c89b83ecfb6cb7510
    Ports:          8080/TCP, 50000/TCP
    Host Ports:     0/TCP, 0/TCP
    State:          Running
      Started:      Fri, 27 Jun 2025 11:05:30 +0530
    Ready:          True
    Restart Count:  0
    Limits:
      cpu:     1
      memory:  2Gi
    Requests:
      cpu:        500m
      memory:     500Mi
    Liveness:     http-get http://:8080/login delay=90s timeout=5s period=10s #success=1 #failure=5
    Readiness:    http-get http://:8080/login delay=60s timeout=5s period=10s #success=1 #failure=3
    Environment:  <none>
    Mounts:
      /var/jenkins_home from jenkins-data (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-csncj (ro)
Conditions:
  Type                        Status
  PodReadyToStartContainers   True 
  Initialized                 True 
  Ready                       True 
  ContainersReady             True 
  PodScheduled                True 
Volumes:
  jenkins-data:
    Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    ClaimName:  jenkins-pv-claim
    ReadOnly:   false
  kube-api-access-csncj:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    Optional:                false
    DownwardAPI:             true
QoS Class:                   Burstable
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:                      <none>


➜  ~ kubectl describe serviceaccount -n devops-tools jenkins-admin         

Name:                jenkins-admin
Namespace:           devops-tools
Labels:              <none>
Annotations:         <none>
Image pull secrets:  <none>
Mountable secrets:   <none>
Tokens:              <none>
Events:              <none>
➜  ~ kubectl get rolebindings,clusterrolebindings --all-namespaces -o wide | grep jenkins

            clusterrolebinding.rbac.authorization.k8s.io/jenkins-admin                                                   ClusterRole/jenkins-admin                                                          104m                                                                                      devops-tools/jenkins-admin
➜  ~ kubectl describe service -n devops-tools jenkins-service

Name:                     jenkins-service
Namespace:                devops-tools
Labels:                   <none>
Annotations:              prometheus.io/path: /
                          prometheus.io/port: 8080
                          prometheus.io/scrape: true
Selector:                 app=jenkins-server
Type:                     NodePort
IP Family Policy:         SingleStack
IP Families:              IPv4
IP:                       10.97.214.43
IPs:                      10.97.214.43
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  32000/TCP
Endpoints:                10.244.0.9:8080
Session Affinity:         None
External Traffic Policy:  Cluster
Internal Traffic Policy:  Cluster
Events:                   <none>

➜  ~ kubectl exec -n devops-tools jenkins-8cc6659c6-p27b8 -- sh -c '
TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
echo "Token exists: $(test -f /var/run/secrets/kubernetes.io/serviceaccount/token && echo "YES" || echo "NO")"
curl -k -H "Authorization: Bearer $TOKEN" https://kubernetes.default.svc.cluster.local:443/api/v1/namespaces | head -20 
'
Defaulted container "jenkins" out of: jenkins, volume-mount-hack (init)
Token exists: YES
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0{
  "kind": "NamespaceList",
  "apiVersion": "v1",
  "metadata": {
    "resourceVersion": "18122"
  },
  "items": [
    {
      "metadata": {
        "name": "default",
        "uid": "f35bf438-ac9c-4827-80d8-8a6fd97f7df8",
        "resourceVersion": "21",
        "creationTimestamp": "2025-06-26T12:54:18Z",
        "labels": {
          "kubernetes.io/metadata.name": "default"
        },
        "managedFields": [
          {
            "manager": "kube-apiserver",
            "operation": "Update",
100  5517    0  5517    0     0   952k      0 --:--:-- --:--:-- --:--:-- 1077k
curl: (23) Failed writing body
➜  ~ 

kindly help if possible

The full error
Error testing connection https://kubernetes.default.svc.cluster.local:443: io.fabric8.kubernetes.client.KubernetesClientException: An error has occurred.

Also i watched a couple of setup videos online, the official one from 4 years ago, why did that video errors had way more context then these errors?

Thanks