Nutshell Series

Fixing Logic App VNet Integration: “Access to the path ‘C:\home\data\Functions\secrets\Sentinels’ is denied.”

Manjunath

If you’re integrating Azure Logic Apps Standard with a VNet and private endpoints, you may encounter this nasty error after deploying your app or modifying your networking configuration:

Access to the path ‘C:\home\data\Functions\secrets\Sentinels’ is denied.

Despite following Microsoft’s recommended steps, the issue may persist. In this post, I’ll break down the actual root causes, explain why the error happens, and offer a practical trick that can resolve it, especially after switching from public to private networking.

🔍 Root Cause

This error usually happens when:

  • Your Logic App is moved from public access to a VNet-integrated private network.
  • The storage account (used to host runtime content and secrets) has private endpoints enabled, but DNS or firewall rules aren’t set up properly.
  • Deployment tools like ARM or Terraform don’t handle the WEBSITE_CONTENTOVERVNET setting correctly during creation.

✅ Microsoft Recommendations to Try First

  1. Enable WEBSITE_CONTENTOVERVNET = 1 in Configuration settings of the Logic App.
  2. Ensure the storage account has:
    • VNet access with correct subnet delegations
    • Private DNS zone linked to your VNet (file, blob, queue, table)
  3. Enable “Allow storage account key access” in the storage account’s Configuration blade.
  4. If using ARM or Terraform:
    • Separate your appSettings into a nested resource of type [Microsoft.Web/sites/config]

But here’s the truth: Even after doing all this, the error may still appear.

🛠️ Trick That Actually Works

If you’re stuck and everything seems configured correctly, try this workaround that’s helped in many real-world deployments:

💡 Scale up your Logic App to WS2 tier temporarily and then scale it back down to WS1.

Why this works:

When switching from public to private storage/VNet, the Logic App runtime may get “stuck” in an inconsistent state, especially regarding storage path mounting or internal config sync.

Scaling up to WS2 forces:

  • A runtime refresh
  • A full reinitialization of the hosting environment
  • Resync of private DNS/storage endpoints

🚀 Step-by-Step: Fix It

  1. Go to your Logic App resource.
  2. Navigate to Scale Up blade.
  3. Change SKU to WS2 (higher tier) and hit Apply.
  4. Wait until the deployment is successful (1–2 mins).
  5. Now go back and revert the SKU back to WS1.

✅ After this step, your Logic App should restart and mount the secret paths correctly.

🧠 Final Thoughts

This issue is not well-documented, but it’s common when moving to private networking in enterprise deployments. Logic Apps tightly depend on the underlying storage account, and improper sync between the app’s network context and the storage endpoints can lead to the above error.

Scaling the app up and down is a safe way to force the platform to re-establish all bindings.

📌 Quick Checklist

  • ✅ VNet Integration configured
  • ✅ Private endpoints enabled for Storage Account
  • ✅ Private DNS zones linked
  • ✅ WEBSITE_CONTENTOVERVNET = 1
  • ✅ Allow storage account key access
  • ✅ Storage access via system-assigned managed identity
  • ✅ Scale-up and scale-down trick applied

💬 Have You Faced This?

Drop your experience or questions in the comments — Azure networking errors can be painful, but you’re not alone!

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