I came across an interesting issue today when I was creating a new ASP.NET AJAX-Enabled Web Application Project in Visual Studio 2005 (with the Visual Studio 2005 SP1 Update for Windows Vista applied) on Windows Vista. After hitting F5 to start the launch the web app in debug mode I received the following error:
Unable to start debugging on the web server. An authentication error occurred while communicating with the web server. Please see Help for assistance.
After a little digging, the following steps solved the problem:
- Open IIS Manager
- Select the virtual directory of the web application
- Click "Advanced Settings"
- Select the "Application Pool" item in the "Behaviour" category
- Change the value from "DefaultAppPool" to "Classic .NET AppPool"
- Restart the website to apply the changes.