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IIS 7 HTTP Error 401.3 - Unauthorized Change the application pool from IUSR to Application Pool.

IIS 7 HTTP Error 401.3 - Unauthorized

Change the application pool from IUSR to Application Pool.

Open the Authentication section. 
Select "Anonymous Authentication"
Click Edit
You'll see the "Anonymous user identity:"
Select Application pool identity. 

That's your fix 

 

 

 

IIS 7 HTTP Error 401.3 - Unauthorized Change the application pool from IUSR to Application Pool.