Category Archives: ASP.NET Classic

Unable to start debugging on a web server. Could not start ASP.NET debugging.

If you attempt to debug an ASP.NET web application and get the following error, you can Google it and find a lot of hits.  There are also numerous posts on StackOverflow for this error but interestingly none of the answers in these posts helped for me.

What worked for me was simple.

The application was being deployed in the DefaultApp pool with the following properties:

  • .NET CLR version = 4.0
  • Managed Pipeline = Integrated
  • Identity = domain/my-user-name

I changed the target application pool to one called .NET 4.5 with the following properties:

  • .NET CLR version = 4.0
  • Managed Pipeline = Integrated
  • Identity =¬†ApplicationPoolIdentity

With this change, I was able to run the application in debug mode.

Happy coding.




Unable to install Microsoft ASP.NET 2.0 AJAX Extensions

The full error message is:

Microsoft ASP.NET 2.0 AJAX Extensions 1.0 requires the .NET Framework 2.0 of .NET Framework 3.0 The .NET Framework installed can be found on the website ( = 76097). Please install a compatible version of the framework and try again.

Yes, this is outdated stuff but when working on legacy ASP.NET applications, you may be required to install ASP.NET 2.0 AJAX Extensions.

If you are working on Windows 7 x64 or later, this is probably a permissions issues. You are probably not logged in to your box as Administrator. You will, therefore, have to run the ASPAJAXExtSetup.msi as Administrator as follows:

  1. Start a command prompt as administrator.
  2. CD to the directory containing the installer
  3. Type the command msiexec /i ASPAJAXExtSetup.msi to run the installer.

This should run the installer, adding a folder C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\v1.0.61025 with associated libraries.

Credit to some answers to this question from here.