Kubernetes CrashLoopBackOff? Step-by-Step Fix with Real Example (2026 Guide)

I pulled a MongoDB Docker image on my Mac, tagged it, pushed it to Azure Container Registry (ACR), and watched the pod crash the moment Kubernetes tried to run it on an Ubuntu node. If you've seen exec format error buried inside your pod logs, you've hit the same wall. Here's exactly what happened and how I fixed it.

But before dig more into fix, lets understand what is the issue exactly and why it occur?

What is CrashloopBackOff?

CrashLoopBackOff is one of the most common Kubernetes pod states that tells you: "The container started, crashed immediately, Kubernetes restarted it, it crashed again — and now I'm backing off before trying again."

Kubernetes applies an exponential backoff delay (10s → 20s → 40s → ... up to 5 minutes) between restart attempts. The CrashLoopBackOff status is not the root cause itself — it is a symptom. The actual reason is always buried in the pod logs or events.

Common cause	Typical log signal
Architecture mismatch (this post)	exec format error
Missing env variable / secret	connection refused / nil pointer
OOMKilled (out of memory)	OOMKilled, exit code 137
Application startup crash	Application-specific error in logs
Wrong entrypoint / CMD	no such file or directory

What was the cause? Why i faced this isse?

I faced this issue because of Architecture mismatch, I use Apple MacBook (M1) it run on