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This guide covers common troubleshooting scenarios and tools for diagnosing and resolving Argo CD issues.

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Troubleshooting Tools

Argo CD provides argocd admin subcommands to validate settings and troubleshoot connectivity issues.

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Settings Validation

Validate Argo CD configuration before applying to production: 
argocd admin settings validate
This command performs basic validation of:
  • ConfigMap settings (argocd-cm)
  • RBAC policies (argocd-rbac-cm)
  • Resource customizations
  • Repository credentials

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Common Issues

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Application Sync Failures

Symptoms: Application shows OutOfSync but sync operation fails or doesn’t start.Diagnosis:
# Check application status
argocd app get <app-name>

# View detailed sync status
kubectl get application <app-name> -n argocd -o yaml

# Check application controller logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-application-controller
Common causes:
  • Invalid manifests in Git repository
  • Resource quota exceeded in target cluster
  • RBAC permissions preventing resource creation
  • Cluster connectivity issues
Solutions:
# Validate manifests locally
kubectl apply --dry-run=client -f manifest.yaml

# Check resource quotas
kubectl describe resourcequota -n <namespace>

# Test cluster connectivity
argocd cluster get <cluster-url>

# Force refresh and sync
argocd app sync <app-name> --force
Symptoms: Application reconciliation fails with Context deadline exceeded.Root cause: Manifest generation is taking too long, exceeding the controller timeout.Solutions:
1

Increase repo server timeout

containers:
- name: argocd-application-controller
  command:
  - argocd-application-controller
  - --repo-server-timeout-seconds=300  # Increase from default 60s
2

Scale repo server

kubectl scale deployment argocd-repo-server -n argocd --replicas=3
3

Optimize repository

  • Use shallow clones for large repositories
  • Enable manifest path annotations for monorepos
  • Reduce parallelism limit if resource-constrained
Symptoms: Sync fails with “insufficient permissions” or RBAC errors.Diagnosis:
# Check AppProject permissions
kubectl get appproject <project-name> -n argocd -o yaml

# Verify cluster RBAC
kubectl auth can-i create deployment -n <namespace> \
  --as=system:serviceaccount:argocd:argocd-application-controller
Solution: Update AppProject to allow resources:
apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: my-project
spec:
  clusterResourceWhitelist:
  - group: '*'
    kind: '*'
  destinations:
  - namespace: '*'
    server: '*'

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Git Repository Issues

Symptoms: Applications can’t connect to Git repositories.Diagnosis:
# Test repository connection
argocd repo get <repo-url>

# Check repo server logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-repo-server
Common causes:
  • Invalid credentials
  • Network connectivity issues
  • SSH key not configured
  • Certificate validation failures
Solutions:For HTTPS repositories:
# Update credentials
argocd repo add https://github.com/org/repo \
  --username <username> \
  --password <token>

# Skip TLS verification (not recommended for production)
argocd repo add https://github.com/org/repo \
  --insecure-skip-server-verification
For SSH repositories:
# Add SSH private key
argocd repo add git@github.com:org/repo.git \
  --ssh-private-key-path ~/.ssh/id_rsa

# Add SSH known hosts
kubectl edit configmap argocd-ssh-known-hosts-cm -n argocd
Symptoms: Intermittent failures resolving Git references (branches, tags).Solution: Increase retry count for Git operations:
containers:
- name: argocd-repo-server
  env:
  - name: ARGOCD_GIT_ATTEMPTS_COUNT
    value: "5"  # Retry failed Git operations

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Cluster Connectivity Issues

Symptoms: Managed cluster shows as “Unreachable” or “Unknown” in UI.Diagnosis:
1

SSH into application controller

kubectl exec -n argocd -it \
  $(kubectl get pods -n argocd \
    -l app.kubernetes.io/name=argocd-application-controller \
    -o jsonpath='{.items[0].metadata.name}') -- bash
2

Export kubeconfig from cluster secret

argocd admin cluster kubeconfig https://<api-server-url> \
  /tmp/kubeconfig --namespace argocd
3

Test connectivity

export KUBECONFIG=/tmp/kubeconfig
kubectl get pods -v 9
Common issues:
  • Expired certificates
  • Invalid bearer tokens
  • Network policies blocking traffic
  • API server URL changed
Solution: Update cluster credentials:
argocd cluster add <context-name> --name <cluster-name> --upsert

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Resource Customization Issues

Custom health checks can be tested before applying to production:
argocd admin settings resource-overrides health \
  ./deployment.yaml \
  --argocd-cm-path ./argocd-cm.yaml
Example health check (Lua):
resource.customizations: |
  argoproj.io/Rollout:
    health.lua: |
      hs = {}
      if obj.status ~= nil then
        if obj.status.phase == "Healthy" then
          hs.status = "Healthy"
          hs.message = "Rollout is healthy"
          return hs
        end
      end
      hs.status = "Progressing"
      hs.message = "Waiting for rollout to complete"
      return hs
Test ignore differences configurations:
argocd admin settings resource-overrides ignore-differences \
  ./deployment.yaml \
  --argocd-cm-path ./argocd-cm.yaml
Shows which fields will be ignored during diff operations.
Execute custom resource actions:
# List available actions
argocd admin settings resource-overrides list-actions \
  /tmp/deployment.yaml \
  --argocd-cm-path /tmp/argocd-cm.yaml

# Run action
argocd admin settings resource-overrides run-action \
  /tmp/deployment.yaml restart \
  --argocd-cm-path /tmp/argocd-cm.yaml

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Performance Issues

Symptoms: Applications take a long time to reconcile and sync.Diagnosis:
# Check reconciliation duration (Prometheus query)
histogram_quantile(0.95, 
  rate(argocd_app_reconcile_bucket[5m])
)

# Check for high K8s API requests
rate(argocd_app_k8s_request_total[5m])
Solutions:
1

Increase controller processors

containers:
- name: argocd-application-controller
  command:
  - argocd-application-controller
  - --status-processors=50
  - --operation-processors=25
2

Enable controller sharding

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: argocd-application-controller
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: argocd-application-controller
        env:
        - name: ARGOCD_CONTROLLER_REPLICAS
          value: "2"
3

Optimize monorepo performance

Use manifest path annotations:
metadata:
  annotations:
    argocd.argoproj.io/manifest-generate-paths: .
Symptoms: Argo CD components OOMKilled or using excessive memory.Common causes:
  • Too many cached resources
  • Large repositories
  • Too many applications per controller
Solutions:For repo server:
spec:
  template:
    spec:
      containers:
      - name: argocd-repo-server
        resources:
          requests:
            memory: 1Gi
          limits:
            memory: 2Gi
        env:
        - name: ARGOCD_EXEC_TIMEOUT
          value: "180s"
For application controller:
env:
- name: ARGOCD_CONTROLLER_REPLICAS
  value: "3"  # Shard applications across replicas
Mount persistent volume for repo server:
volumeMounts:
- mountPath: /tmp
  name: tmp-dir
volumes:
- name: tmp-dir
  persistentVolumeClaim:
    claimName: argocd-repo-server-pvc
Symptoms: High argocd_repo_pending_request_total metric.Cause: Multiple applications in same repository causing sequential processing.Solutions:
  • Enable concurrent processing (create .argocd-allow-concurrency file)
  • Scale repo server horizontally
  • Split applications into separate repositories
  • Use manifest path annotations

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Application Health Issues

Cause: No health check defined for resource type.Solution: Add custom health check:
apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
data:
  resource.customizations: |
    my.custom.resource/MyKind:
      health.lua: |
        hs = {}
        if obj.status ~= nil and obj.status.ready then
          hs.status = "Healthy"
        else
          hs.status = "Progressing"
        end
        return hs
Diagnosis:
# Check resource status
argocd app get <app-name> --show-operation

# Check individual resource health
kubectl get <resource> -n <namespace>
kubectl describe <resource> <name> -n <namespace>
Common causes:
  • Pods stuck in ImagePullBackOff
  • Insufficient resources (CPU/memory)
  • Failing health checks
  • Init containers not completing

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Debugging Commands

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Log Collection

# Application controller logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-application-controller --tail=100

# Repo server logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-repo-server --tail=100

# API server logs
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-server --tail=100

# Follow logs in real-time
kubectl logs -n argocd -l app.kubernetes.io/name=argocd-application-controller -f

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Resource Inspection

# Get application details
argocd app get <app-name>

# Get application as YAML
kubectl get application <app-name> -n argocd -o yaml

# Get application history
argocd app history <app-name>

# Get application events
kubectl get events -n argocd --field-selector involvedObject.name=<app-name>

# Get all applications
argocd app list

# Get application resources
argocd app resources <app-name>

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Configuration Verification

# Check ConfigMaps
kubectl get configmap -n argocd argocd-cm -o yaml
kubectl get configmap -n argocd argocd-rbac-cm -o yaml
kubectl get configmap -n argocd argocd-cmd-params-cm -o yaml

# Check secrets
kubectl get secret -n argocd argocd-secret -o yaml

# Validate settings
argocd admin settings validate

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Getting Help

GitHub Issues

Search existing issues or create new ones: argoproj/argo-cd

Slack Community

Join the Argo CD community: CNCF Slack #argo-cd

Documentation

Official Argo CD docs: argo-cd.readthedocs.io

Stack Overflow

Ask questions with the argocd tag: stackoverflow.com