25 Most Common Kubernetes Errors and How to Solve Them

In Kubernetes, users frequently encounter errors during deployment, scaling, or maintenance. Here are 25 of the most frequent Kubernetes errors and how to resolve them with specific commands.

1. Error: CrashLoopBackOff
   Cause: A pod repeatedly fails to start, typically due to an issue with
   the container itself.
   Solution:
   Check the logs of the failing pod:

   kubectl logs <pod_name>
   Correct the underlying issue, often related to missing dependencies or
   configuration errors

2. Error: ImagePullBackOff
   Cause: Kubernetes can't pull the container image.
   Solution:
   Verify the image name and tag are correct
   kubectl describe pod <pod_name>
   Ensure you are using the correct Docker image and repository.

3. Error: ImagePullBackOff
   Cause: Failure to pull the specified container image from the
   registry.
   Solution: Check your image and registry credentials
   kubectl get pods -o wide
   Ensure your image is available or the credentials to pull from a private repository are correct.

4. Pod Stuck in Pending State
   Cause: Kubernetes can't find resources (CPU, memory) to schedule the
   pod.
   Solution: Check for node capacity and resource limits
   kubectl describe pod <pod_name>
   Increase resource limits or add nodes to the cluster.

5. Error: Node NotReady
   Cause: The node has gone offline or has insufficient resources.
   Solution: Check node status
   kubectl get nodes
   Fix issues such as networking or resource exhaustion.

6. Container OOMKilled
   Cause: The container used more memory than was allocated.
   Solution: Increase memory limits
   kubectl describe pod <pod_name>

7. Error: Unauthorized Error While Accessing the API Server
   Cause: The kubeconfig file has wrong credentials or is expired.
   Solution: Update the kubeconfig file
   kubectl config view
   Fix credentials by generating a new kubeconfig or ensuring correct access permissions.

8. Error: PersistentVolumeClaim (PVC) Not Bound
   Cause: No PersistentVolume is available to match the PVC request.
   Solution: Check available PersistentVolumes
   kubectl get pv
   Ensure the requested storage class matches an available PersistentVolume.

9. Error: Pod Evicted
   Cause: The node ran out of resources (like disk or memory), causing
   Kubernetes to evict the pod.
   Solution: Check resource limits and node status
   kubectl describe pod <pod_name>
   Free up resources or add more capacity.

10. Error: Kubelet Not Running
    Cause: Kubelet service on a node has stopped or failed.
    Solution: Restart Kubelet on the node
    sudo systemctl restart kubelet

11. Error: DNS Issues in Cluster
    Cause: DNS resolution is failing for service discovery within the
    cluster.
    Solution: Check CoreDNS pods
    kubectl get pods -n kube-system -l k8s-app=kube-dns
    Restart CoreDNS pods if needed:
    kubectl delete pod -n kube-system -l k8s-app=kube-dns

12. Error: Kubectl Context Not Set Correctly
    Cause: Incorrect or missing Kubernetes context.
    Solution: Set the correct context
    kubectl config use-context <context_name>

13. Error: Service Not Exposing
    Cause: Service is not exposing the application properly.
    Solution: Check the service configuration
    kubectl get svc <service_name>
    Ensure proper type (ClusterIP, NodePort, LoadBalancer) and port configuration.

14. Error: Cannot Attach Volume
    Cause: Volume can't be attached to the pod, possibly due to multiple
    mounts.
    Solution: Check for pod conflicts
    kubectl describe pod <pod_name>
    Ensure no other pod is using the same volume.

15. Error: Pod in Terminating State
    Cause: Pod termination is taking too long, possibly due to stuck
    processes or finalizers.
    Solution: Force delete the pod
    kubectl delete pod --grace-period=0 --force

16. Error: Insufficient CPU or Memory
    Cause: The requested resources exceed node capacity.
    Solution: Check node and pod resource usage

    kubectl top nodes
    kubectl top pods
    Either reduce pod resource requests or scale the cluster.

17. Error: RBAC Forbidden Error
    Cause: The service account does not have the necessary permissions.
    Solution: Create or modify a RoleBinding
    kubectl create rolebinding rolebinding-name --clusterrole= --serviceaccount=<namespace> :serviceaccount --namespace=<namespace>

18. Error: HPA Not Working
    Cause: HPA metrics aren't available.
    Solution: Ensure the metrics-server is running
    kubectl get apiservices | grep metrics

19. Error: Kube-apiserver Fails to Start
    Cause: Misconfiguration or failure of kube-apiserver.
    Solution: Check the apiserver logs
    journalctl -u kube-apiserver
    Correct any configuration errors found.

20. Error: Service Mesh Issues (e.g., Istio)
    Cause: Misconfiguration of sidecar proxies or traffic routing.
    Solution: Check pod logs and services
    Service mesh connectivity issues

21. Error: Scheduler Fails to Bind Pod
    Cause: No node meets the requirements to schedule the pod.
    Solution: View scheduler logs
    kubectl logs <pod_name> -c istio-proxy
    Verify Istio configuration and virtual services.

22. Error: Invalid Resource Requests
    Cause: Resource requests are higher than the node limits.
    Solution: Adjust resource requests and limits
    Eg:
    resources:
    requests:
    memory: "64Mi"
    cpu: "250m"

23. Error: Ingress Controller Not Working
    Cause: Ingress resource or controller misconfiguration.
    Solution: Check Ingress controller pods and logs
    kubectl get pods -n ingress-nginx
    kubectl logs <ingrees_controller_pod>

24. Error: Failed to List Nodes
    Cause: Kubelet can't communicate with the API server.
    Solution: Check network configuration and API server status
    kubectl get nodes

25. Error: Certificate Expired
    Cause: TLS certificates used by Kubernetes components have expired.
    Solution: Renew the certificates
    sudo kubeadm alpha certs renew all

    Conclusion:
    These are some of the most common Kubernetes issues you might encounter Across Staging/Dev/Production environments. The solutions listed above should help you quickly diagnose and fix these problems. Always ensure you are using proper configurations, monitor your cluster’s health, and apply best practices to prevent these issues from happening.