Common scenarios

Excellent — this is a very interview-relevant and real-world question 👏

Here’s a full guide on common ArgoCD failures and troubleshooting scenarios, grouped by type, with clear explanations and sample answers you can use in interviews or projects.

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🚨 1. App stuck in “OutOfSync”

Scenario: ArgoCD UI shows app status as OutOfSync even after committing changes to Git.

Root Cause:

• Auto-sync is disabled (prune/selfHeal: false)

• Branch mismatch (ArgoCD tracking main, changes pushed to feature branch)

• File path mismatch in spec.source.path

Fix:

• Enable auto-sync:

  syncPolicy:
    automated:
      prune: true
      selfHeal: true

• Verify correct path:

  kubectl -n argocd get app myapp -o yaml | grep path

• Sync manually via UI or CLI:

  argocd app sync myapp

Interview Tip:

“OutOfSync means Git and live cluster differ. Usually happens due to branch mismatch, manual cluster edits, or auto-sync being off. I verify the targetRevision and sync policy, then perform a manual sync if needed.”

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🧱 2. Application stuck in “Progressing”

Scenario: ArgoCD keeps showing Progressing or Syncing and never reaches Healthy.

Root Cause:

• Pod crash loops (CrashLoopBackOff)

• Deployment readiness probes failing

• Missing dependencies (e.g., DB service not ready)

• ArgoCD waiting for health check success

Fix:

kubectl get pods -n <namespace>
kubectl describe pod <pod-name>

Check logs:

kubectl logs <pod-name> -n <namespace>

Interview Tip:

“Progressing usually means K8s resources aren’t healthy yet. I check pod logs, describe events, and verify readiness probes.”

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🔑 3. “Permission denied” or “unauthorized”

Scenario: ArgoCD fails to pull from a private Git repo or deploy to the cluster.

Root Cause:

• Missing SSH key or token in argocd-secret

• ServiceAccount in ArgoCD lacks cluster role permissions

• Wrong repoURL format

Fix:

• Add Git credentials:

  argocd repo add [email protected]:ORG/REPO.git --ssh-private-key-path ~/.ssh/id_rsa

• Check service account binding:

  kubectl get clusterrolebinding argocd-application-controller

Interview Tip:

“Usually this happens due to missing Git credentials or RBAC issues. I check repo connections in the UI and verify the service account’s permissions.”

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🌐 4. “Repo not accessible” or “Unable to clone repo”

Scenario: ArgoCD fails to fetch the Git repository.

Root Cause:

• Wrong repo URL (https vs ssh)

• Internet/DNS issues in the cluster

• Repo moved or renamed

Fix:

argocd repo list
argocd repo rm <repo>
argocd repo add <correct-repo-url>

Interview Tip:

“I check ArgoCD repo connection health, DNS resolution in the Argo pod, and ensure the repo uses the same access type (SSH/HTTPS) as configured.”

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🧩 5. Image Updater not updating

Scenario: Image Updater is configured, but the new Docker image version isn’t deployed.

Root Cause:

• Missing annotation or incorrect image name

• ArgoCD app is not using Kustomize/Helm values for image tag

• No commit permission to repo

Fix: Verify annotation:

argocd-image-updater.argoproj.io/image-list: myapp=myrepo/myapp

Check logs:

kubectl logs -n argocd deploy/argocd-image-updater

Interview Tip:

“I validate the annotations and ensure Image Updater has Git commit access via token or SSH. Also, the app must reference image tags through Kustomize or Helm values.”

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🧾 6. Drift due to manual kubectl changes

Scenario: A developer edited a Deployment manually (kubectl edit), causing config drift.

Root Cause:

• selfHeal disabled

• ArgoCD doesn’t auto-revert changes

Fix:

• Enable self-heal:

  syncPolicy:
    automated:
      selfHeal: true

• Or manually resync:

  argocd app sync myapp

Interview Tip:

“I prefer enabling self-heal in production to prevent drift and enforce GitOps discipline.”

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📦 7. “Invalid Kustomization” or “Manifest generation error”

Scenario: ArgoCD UI shows manifest generation error or invalid kustomization.

Root Cause:

• Bad YAML syntax

• Missing kustomization.yaml or wrong path

• Helm/Kustomize plugin misconfigured

Fix:

kubectl -n argocd logs deploy/argocd-repo-server

Validate locally:

kustomize build <path>

Interview Tip:

“Manifest generation failures mean Argo can’t render manifests. I run kustomize build locally to debug syntax or path issues.”

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⚙️ 8. “Sync failed” due to missing CRDs

Scenario: ArgoCD tries to apply a CR (Custom Resource) before its CRD is installed.

Root Cause:

• Wrong apply order

• CRDs defined in another Argo app

• Helm chart dependency missing

Fix:

• Add sync waves:

  argocd.argoproj.io/sync-wave: "0"

• Deploy CRDs before CRs.

Interview Tip:

“This happens when CRDs aren’t yet available. I use sync waves or separate Argo apps for CRDs.”

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🧰 9. “Application missing or deleted”

Scenario: An app disappears or gets recreated repeatedly.

Root Cause:

• prune: true deleting resources outside Git

• Namespace ownership overlap

• App-of-Apps model misconfigured

Fix: Check event logs:

kubectl -n argocd describe app myapp

Ensure each app manages its own subpath/namespace.

Interview Tip:

“When multiple Argo apps point to overlapping paths, pruning can delete others’ resources. I isolate each app per namespace.”

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🧠 10. “Cluster connection lost”

Scenario: ArgoCD can’t access the Kubernetes cluster it’s managing.

Root Cause:

• Service account tokens expired

• Cluster context removed

• Network or API server issue

Fix: Re-add the cluster:

argocd cluster add <context-name>

Interview Tip:

“Cluster connection loss usually happens due to expired service account tokens or RBAC misconfigurations. I check cluster credentials and re-add if required.”

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💬 Bonus — Best One-Line Answers for Interview

Question	Perfect Short Answer
“Why is app OutOfSync?”	Git and live cluster differ — auto-sync disabled or branch mismatch.
“How to handle drift?”	Enable selfHeal: true or perform manual sync.
“What’s prune used for?”	Automatically deletes resources removed from Git.
“How do you debug sync failures?”	Check argocd-repo-server logs and use argocd app get <app>.
“What are sync waves?”	Control the order in which resources apply, useful for CRDs or dependencies.

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Would you like me to give you a ready-made ArgoCD troubleshooting cheatsheet (markdown/pdf) you can carry to interviews and use in real-world debugging?