Kubernetes CrashLoopBackOff – Causes and Fixes (2026)

What is CrashLoopBackOff? #

CrashLoopBackOff means your container is starting, crashing, and Kubernetes keeps restarting it in a loop. It is not a single error — it is a symptom of something else failing inside your container.

Common Causes #

1. Application error on startup Your app crashes immediately after starting due to a bug or missing dependency.

2. Wrong environment variables Missing or incorrect env vars cause the app to fail before it runs.

3. Missing ConfigMap or Secret Pod references a ConfigMap or Secret that does not exist in the namespace.

4. Insufficient resources Container hits memory limit and gets killed immediately.

5. Wrong container image Image does not exist or wrong tag specified.

How to Diagnose #

Step 1 — Check pod status:

kubectl get pods

Step 2 — Check pod logs:

kubectl logs <pod-name> --previous

Step 3 — Describe the pod:

kubectl describe pod <pod-name>

Look for Events section at the bottom — it tells you exactly what failed.

How to Fix #

Fix 1 — Check your application logs first:

kubectl logs <pod-name> --previous

Read the actual error. 90% of the time the fix is obvious from the logs.

Fix 2 — Verify environment variables:

kubectl describe pod <pod-name> | grep -A 10 Environment

Fix 3 — Check if ConfigMap exists:

kubectl get configmap -n <namespace>

Fix 4 — Check resource limits:

kubectl describe pod <pod-name> | grep -A 5 Limits

Increase memory limit in your deployment yaml if needed.

Fix 5 — Verify image exists:

kubectl describe pod <pod-name> | grep Image

Summary #

CrashLoopBackOff always has a root cause. Never restart the pod blindly — always check logs first with kubectl logs –previous. That single command solves 90% of cases.