Software⏱️ 2 min read📅 2026-05-31

How to Fix: Login failed for user 'IIS APPPOOL\ASP.NET v4.0'

IIS 7 configuration issue with ASP.NET v4.0 pool target framework.

Quick Answer: Check the IIS 7 pool settings to ensure that the .NET CLR version is set to 'v4.0' and the 'Integrated Pipeline Mode' is enabled.

[2 paragraphs intro]

⚠️ Common Causes

  • Incorrect ASP.NET pool configuration, leading to a mismatch between the target framework and the application's framework.

🛠️ Step-by-Step Verified Fixes

Method 1: App Pool Configuration Adjustment

  1. Step 1: Open the IIS Manager, navigate to the Default Web Site, and select the ASP.NET v4.0 pool.

Method 2: Update Application Pool Identity

  1. Step 1: In the Default Web Site, right-click on the application pool, select Advanced settings, and update the Identity to a new identity.

💡 Conclusion

By adjusting the ASP.NET pool configuration and updating the application pool identity, you should be able to resolve the 'Login failed for user IIS APPPOOLspotASP.NET v4.0' error.

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