Kubernetes is a powerful container orchestration platform, but troubleshooting issues within a cluster can be daunting. Whether you’re dealing with pod failures, networking issues, or resource constraints, understanding how to diagnose and resolve problems efficiently is crucial.

This blog provides a structured approach to Kubernetes troubleshooting, covering common errors, debugging techniques, and best practices to maintain a healthy cluster. Kubernetes troubleshooting is the process of identifying, diagnosing, and resolving issues in Kubernetes clusters, nodes, pods, or containers.

Why Is Kubernetes Troubleshooting Challenging?

Kubernetes troubleshooting is tough because:

• It’s a complex system. Kubernetes has many moving parts—containers, nodes, and services—all working together. If something goes wrong, figuring out the exact problem can be difficult.
• Different teams, different methods. Kubernetes clusters often host microservices built by multiple teams. Each team may use different coding styles, programming languages, and tools. This lack of uniformity can create conflicts, making debugging harder.
• Collaboration is key. Solving problems in Kubernetes requires teamwork among developers, operations, and security experts. Clear communication helps resolve issues faster.
• Monitoring tools help. Using tools for tracking system health, like monitoring and observability platforms, makes it easier to spot issues early and fix them efficiently.

What Is Kubernetes Troubleshooting?

Kubernetes troubleshooting is the process of finding and fixing performance problems in a Kubernetes setup. Some common issues include:

• Containers or Pods won’t start. They may fail completely or take too long to launch.
• Slow applications. Apps may take longer than expected to respond to user requests.
• Network problems. Some apps may struggle to connect properly.
• Unexpected crashes. Containers or Pods might stop working suddenly.
• Incorrect Pod placement. Pods may be assigned to the wrong nodes, leading to resource shortages.
• Poor resource limits. If resource settings aren’t optimized, applications may run slower than they should.

These are just a few examples. In a real-world Kubernetes environment, many different performance issues can arise, and troubleshooting them quickly is crucial to keeping everything running smoothly.

The Three Pillars of Kubernetes Troubleshooting

Just like observability has its three main tools—metrics, logs, and traces—troubleshooting issues in Kubernetes also depends on three core areas: Understanding, Managing, and Preventing problems.

1. Understanding

The first step is to figure out what’s wrong. You need to see how your applications (workloads) are running, find out if something’s broken, and understand what’s needed to fix it.

Example:
Let’s say one of your apps is slow to respond. You use kubectl to check the list of Pods and inspect their logs. You find that one Pod has crashed. Then you check the resource usage on the node where it was running and see that the CPU was maxed out. That’s likely why the Pod crashed. You dig a bit deeper and realize that the Pod was part of a DaemonSet, so it had to run on that specific node—and Kubernetes couldn’t move it elsewhere.

2. Managing

Once you know what went wrong, the next step is to fix it.

Continuing the example:
To solve the problem, you could change the DaemonSet so the Pod can run on a different node. Or you might replace the DaemonSet with a Deployment, which allows Kubernetes to schedule the Pod on any available node. Another option could be to give the current node more CPU—if that’s possible. But this only makes sense if the Pod must stay on that specific node.

3. Preventing

After fixing the issue, the final step is making sure it doesn’t happen again.

Prevention tips:

• Set up alerts to warn you when a node’s CPU usage goes above, say, 80%.
• Use node autoscaling (if your setup supports it) so Kubernetes can automatically add more nodes when needed.

Just remember: autoscaling only works if Kubernetes is allowed to move Pods around—so if you’re using a DaemonSet that locks a Pod to one node, autoscaling might not help in that case.

Troubleshooting Common Kubernetes Errors

If you’re running into one of these common Kubernetes issues, here’s a quick guide to help you identify the cause and fix it:

• CreateContainerConfigError
  This usually means there’s a problem with your Pod configuration—like a missing secret, wrong environment variable, or bad volume mount.
• ImagePullBackOff / ErrImagePull
  These errors happen when Kubernetes can’t pull the container image. Check if the image name is correct, the registry is accessible, and you have the right credentials (if needed).
• CrashLoopBackOff
  Your container keeps crashing and restarting. This often points to problems in the application code, bad configs, or missing dependencies. Check the logs to find the root cause.
• Node Not Ready
  Kubernetes marks a node as “Not Ready” when it’s unhealthy. This could be due to network issues, kubelet failure, or resource exhaustion. Check the node status and system logs to investigate.

1. Fixing the CreateContainerConfigError in Kubernetes

The CreateContainerConfigError usually happens when a Pod is trying to use a missing Secret or ConfigMap.

• Secrets store sensitive data like passwords or tokens.
• ConfigMaps store configuration data in key-value pairs, often shared across Pods.

How to Identify the Problem

1. Check the Pod status:

kubectl get pods

Look for a status like this:

NAME                 READY   STATUS                       RESTARTS   AGE
pod-missing-config   0/1     CreateContainerConfigError   0          2m27s

2. Describe the Pod to find the root cause:

kubectl describe pod pod-missing-config

Look for an error like:

Warning  Failed  ...  Error: configmap "my-configmap" not found

How to Fix It

3. Check if the missing ConfigMap exists:

kubectl get configmap my-configmap

• If you see Error from server (NotFound), the ConfigMap is missing.
• You’ll need to create it using the appropriate configuration. Kubernetes ConfigMap docs can help.

4. Verify the ConfigMap was created:

kubectl get configmap my-configmap -o yaml

This shows its contents and confirms it exists.

5. Check the Pod status again:

kubectl get pods

You should now see something like:

NAME                 READY   STATUS    RESTARTS   AGE
pod-missing-config   1/1     Running   0          2m51s

2. Fixing ImagePullBackOff or ErrImagePull in Kubernetes

These errors mean your Pod can’t start because it failed to download the container image from a registry. Kubernetes won’t run the Pod until it successfully pulls the image.

How to Identify the Problem

1. Check Pod status:

kubectl get pods

Look for one of these statuses:

NAME     READY   STATUS             RESTARTS   AGE
mypod    0/1     ImagePullBackOff   0          58s

or

mypod    0/1     ErrImagePull       0          58s

How to Fix It

2. Get detailed info about the Pod:

kubectl describe pod mypod

Look for messages that explain why the image pull failed. Common issues include:

1. Incorrect image name or tag

A typo in the image name or tag is a common cause. Try pulling the image manually to confirm:
If the image is incorrect, fix the image name or tag in your deployment YAML and reapply it.

docker pull your-image-name:tag

If the image is incorrect, fix the image name or tag in your deployment YAML and reapply it.

2. Authentication failure

If your image is in a private registry, Kubernetes needs proper credentials.Check if the Secret holding your registry credentials exists and is correctly referenced in your Pod spec.Make sure your node or Pod has the required RBAC permissions to pull the image.Try pulling the image manually with:

docker login docker pull your-private-image

If the pull works manually but fails in Kubernetes, update your image pull secret or service account.

After the Fix

Once you’ve resolved the issue, check the Pod again:

kubectl get pods

You should see the Pod status change to:

mypod    1/1     Running   0   2m

3. Fixing CrashLoopBackOff in Kubernetes

The CrashLoopBackOff error means your Pod keeps crashing and restarting. This can happen for several reasons, such as missing resources, volume mount issues, or incorrect Pod settings.

How to Identify the Problem

1. Check Pod status:

kubectl get pods

You’ll see output like this:

NAME       READY   STATUS             RESTARTS   AGE
mypod      0/1     CrashLoopBackOff   3          58s

The increasing RESTARTS count shows the Pod is failing repeatedly.

How to Fix It

2. Describe the Pod for more details:

kubectl describe pod mypod

Look through the output to find what’s causing the crash. Common causes include:

• Not enough resources
  The node may not have enough CPU or memory. Fix this by:
  • Manually evicting other Pods to free up space.
  • Scaling your cluster to add more nodes.
• Volume mount failure
  If the Pod can’t mount a volume, check:
  • That the volume is correctly defined in the Pod YAML.
  • That the PersistentVolume or PersistentVolumeClaim exists and is properly configured.
• Using hostPort
  If your Pod is using a hostPort, only one Pod can use that port on a given node. This can block scheduling.
  • Try removing hostPort and use a Kubernetes Service instead for network access.

After the Fix

After making changes, re-deploy your Pod and check the status again:

kubectl get pods

You should see:

mypod   1/1     Running   0   2m

4. Fixing Node Not Ready in Kubernetes

A Node Not Ready status means that a worker node has become unresponsive—usually due to a crash, shutdown, or network failure. Any Pods running on that node, especially stateful ones, become unavailable.

If the node stays in NotReady status for more than 5 minutes (by default), Kubernetes marks the Pods on it as Unknown and tries to reschedule them to another node, where their status becomes ContainerCreating.

How to Identify the Problem

1. Check node status:

kubectl get nodes

Look for NotReady in the output:

NAME        STATUS     AGE    VERSION
mynode-1    NotReady   1h     v1.2.0

2. Check if Pods are being rescheduled:

kubectl get pods -o wide

You might see the same Pod listed twice—once on the failing node and once being recreated on another:

NAME     READY   STATUS              RESTARTS   AGE   IP      NODE
mypod    1/1     Unknown             0          10m   [IP]    mynode-1
mypod    0/1     ContainerCreating   0          15s   [none]  mynode-2

How to Fix It

Option 1: Let Kubernetes handle it (if the node recovers):

• When the failed node comes back online, Kubernetes:
  • Deletes the old Pod.
  • Detaches volumes from the failed node.
  • Reschedules the Pod on a healthy node.
  • The Pod status moves from ContainerCreating to Running.

This happens automatically within about 5 minutes.

Option 2: Manually recover if the node doesn’t come back:

• Remove the failed node:

kubectl delete node mynode-1

• Delete the Pod stuck in Unknown status:

kubectl delete pod mypod --grace-period=0 --force -n [namespace]

This forces Kubernetes to reschedule the Pod on a healthy node right away.

After the Fix

Run:

kubectl get pods

You should now see your Pod in a healthy state:

NAME       READY   STATUS    RESTARTS   AGE
mypod      1/1     Running   0          1m

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