While creating Web API project targeting ASP.NET Core 3.0 using the template the following the settings in launchSetting.json file

Given iisExpress was selected as hosting platform the expectation is that the end point is accessible in the browser, but instead received the following:

The error is referring to a setting in IIS even though the WebApi is configured to run under IIS Express within Visual Studio IDE. The solution will be to open Configuration Editor in IIS and set Impersonate t= False as indicated below

 

Navigate to system.web/identity and set impersonate = false and restart IIS

The WebApi should now be accessible in the browser