Software⏱️ 3 min read📅 2026-06-15

How to Fix Error 401 Error – IIS Server - HTTP Error 401.3 - Unauthorized

IIS server configuration issue fix

Quick Answer: Check IIS ACL settings and ensure proper encryption configurations for the resource.

📋 Table of Contents

  1. 🔍 Why This Happens
  2. 🔧 Proven Troubleshooting Steps
  3. 💡 Conclusion

IIS Server HTTP Error 401.3 - Unauthorized error occurs when you try to access a directory or page on your IIS server that is protected by an access control list (ACL) configuration or encryption settings.

This error can be frustrating, especially if you're new to IIS or web development, as it prevents you from accessing the resources you need to test and deploy your applications.

🔍 Why This Happens

  • The HTTP Error 401.3 - Unauthorized error is primarily caused by incorrect ACL configurations on the IIS server. This can occur when the permissions for a directory or file are set too restrictive, preventing the web server from accessing the resource.
  • Another possible cause of this error is the use of encryption settings that restrict access to certain resources.

🔧 Proven Troubleshooting Steps

Configuring Correct ACL Settings

  1. Step 1: Step 1: Open the IIS Manager and navigate to the 'Security' tab for the site or application you're trying to access.
  2. Step 2: Step 2: Click on the 'Edit' button next to the 'Access' section to open the ACL configuration window.
  3. Step 3: Step 3: In the ACL configuration window, click on the 'Add' button to add a new user or group that has permission to access the resource.
  4. Step 4: Step 4: Select the correct permissions for the user or group, such as 'Read and Execute', depending on your needs.
  5. Step 5: Step 5: Click 'OK' to save the changes and apply the updated ACL settings.

Disabling Encryption Settings

  1. Step 1: Step 1: Open the IIS Manager and navigate to the 'Security' tab for the site or application you're trying to access.
  2. Step 2: Step 2: Click on the 'Edit' button next to the 'Access' section to open the ACL configuration window.
  3. Step 3: Step 3: In the ACL configuration window, click on the 'Disable' button next to the encryption settings that are restricting access to the resource.
  4. Step 4: Step 4: Confirm that you want to disable the encryption settings by clicking 'OK'.
  5. Step 5: Step 5: Restart the IIS server to apply the changes.

💡 Conclusion

By following these steps, you should be able to resolve the HTTP Error 401.3 - Unauthorized error on your IIS server and gain access to the resources you need to test and deploy your applications.

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