Asp.net Debugging Errors and Solutions

Exception: The server does not support debugging of ASP.NET or ATL server applications.

If you have an XP Pro or W2K Pro machine, you may need to think about the order of installation between VS.net 7.0 and IIS. If you install IIS after VS.net 7.0, you will get this error. In this case, please register “aspnet_isapi.dll” with “aspnet_regiis.exe –i”.


Exception: Error while trying to run project: Unable to start debugging on the web server. The project is not configured to be debugged.

When trying to run/debug my ASP.Net web app from VS.NET (2003) I get this error:
Error while trying to run project: Unable to start debugging on the web server. The project is not configured to be debugged.

This was caused because I had renamed the virtual dir that the project resides in - and because of this IIS had decided to revert the dir from an application to a dir.

To resolve simply make it an app again via the IIS Management tool:
Within the IIS management tool, select your virtual dir.
Right-click and select Properties
In the Properties dialog box, click on the Create button.


Exception: Unable to start debugging on the web server

Your IIS application of IIS is not configured to use “integrated Windows authentication”. Please make sure that the “integrated windows authentication” checkbox on the “authentication method” dialog box is checked.


Exception: The project is not configured to be debugged.

You need to make sure that your web is configured for debugging. To do this, you need set “debug = true” in the “web.config” file. You may find this file in your web project folder.


Exception: Could not start ASP.NET or ATL server debugging.

You may have installed “IIS Lockdown” tool. If so, Please find “urlscan.ini” file, and add “DEBUG”(case sensitive) into “[allowverbs]” section in “urlscan.ini” file.


Exception: Access is denied.

You may be the member of “Debugger users” group, but you don’t have the right to debug the aspnet worker process, because you are not the “aspnet” user account or the member of “Administrators” group. Please add your user account to the “Administrators” group on the machine.


Exception: The debugger is not properly installed.

If you see this problem, please check debugging with console application project. And if the console application project shows the error message like

It means that your .Net framework is not installed properly. So you need to register “mscordbi.dll” manually by executing “regsvr32 mscordbi.dll”.


Exception: Do not have permission to debug the server

Problem 1: Make sure that “Integrated Windows Authentication” is enabled. Probably, you enabled only “Basic authentication” for Directory security of IIS.

Problem 2: If you are using “Integrated Windows authentication”, you need to make sure that your user account has full control on the directory of the IIS.

Problem 3: If you created the web project with a full machine name (like “machinename.domainname.something”), the web site is recognized as “Internet” site. So the default setting of IE will impact on the behavior of log on. In this case, you need to enable logging on with your current user account in “Internet” area with IE setting. But it is not the default setting of IE, so you’d be better off if you create project with only the machine name.


Breakpoint is not working, Can start debugging without error message, but breakpoints are not hit.

You started debugging with “F5” and it looks like debugging is started properly, and IE is launched properly. But you can’t hit a breakpoint on my code behind code.

Problem 1: Please make sure that “asp.net debugging” is enabled in the properties of project.

In the case of VB project, the UI is different. But you can recognize the equivalent one easily.

Problem 2: Please make sure that the expected DLL is loaded with matched debug symbol file. You can check it with “Modules” window.


Exception: Server side-error occurred on sending debug HTTP request.

Problem 1: Your web application doesn’t have an Application name. Please check the properties of the web project using the IIS MMC to ensure that your web project has an application name

You need to create an application name for debugging.

Problem 2: If you are using the NTFS file format, please make sure that “aspnet” has proper privilege on “wwwroot” or your folder for virtual directory to access and write on the folders.