You may face an Asp.Net error while running your Web Application Project in Debug mode using IIS Express:

“an asp.net setting has been detected that does not apply in integrated managed pipeline mode”

This error means that the framework expects the App Pool to be running the Managed Pipeline Mode as Classic. In Classic mode, managed application events are executed by using ISAPI.

There are other ways to suppress the error by making an entry in the Web.Config file to set the validateIntegratedModeConfiguration to false. But it is better to set the correct application pool.

Select your Project under the Solution and press F4 on your keyboard to access the Project Properties as shown below:

Also, you can enable/disable the Authentication for Anonymous and Windows modes.

Check this post on how to create Virtual Directory in IIS Express.