After Migrating the application to work with the Integrated .NET mode, you might come across a problem: Server Error in Application "WebSiteName" - HTTP Error 401.3 – Unauthorized
HTTP Error 401.3 – Unauthorized
Resolving HTTP Error 401.3 – Unauthorized Error
Click on Authentication and click edit after choosing Anonymous Authentication. In the opening window select Application Pool identity and click OK.
Resolving HTTP Error 401.3 – Unauthorized Error - Application Pool Identity