PRB: "HTTP/1.1 500 Internal Server Error" Error Message When You Have Multiple ASP.NET Applications That Use the Same Application Pool with Different Script-Mapped Versions

When you try to create a new Microsoft ASP.NET 1.1 application after you change the script mapping of the existing ASP.NET 1.1 Web application to ASP.NET 1.0 on a Microsoft Windows Server 2003-based computer, you may receive the following error message:

This issue occurs because Windows Server 2003 does not allow two versions of ASP.NET to run in the same application pool.

To work around the problem, do one of the following:

• Restart the IIS before you create a new ASP.NET 1.1 application. At the command prompt, type the following command:
  iisreset
  -or-
• Create an ASP.NET application in a separate application pool. Create the script-mapped application (ASP.NET 1.0) in a separate application pool -- for example, in the ScriptMapappPool application pool. Then, create a new ASP.NET 1.1 application in an application pool other than ScriptMapappPool. For more information about how to create an application pool, visit the following Microsoft Web site:
  Configuring Application Pools
  http://msdn2.microsoft.com/en-us/library/1kdfe21k(VS.80).aspx

This behavior is by design.

Create a New ASP.NET 1.1 Web Application

1. In Windows Server 2003, start Microsoft Visual Studio .NET 2003.
2. Create a new ASP.NET Web application project by using Microsoft Visual Basic .NET or Microsoft Visual C# .NET. Name the project as ScriptMap10. By default, WebForm1.aspx is created.
3. On the Build menu, click Build Solution.
4. Close the Visual Studio IDE.

Configure the Script Map of the Application to ASP.NET 1.0

1. Click Start, and then click Run.
2. In the Open box, type cmd, and then click OK.
3. At a command prompt, locate the following directory path:
   %windir%\Microsoft.NET\Framework\v1.0.3705
4. To configure the application to ASP.NET 1.0 in Microsoft Internet Information Services (IIS), type the following command:
   aspnet_regiis -s w3svc/1/root/ScriptMapTest
5. To view the application, type the following URL in Microsoft Internet Explorer:
   http://localhost/ScriptMapTest/WebForm1.aspx

Create a New ASP NET 1.1 Application

1. Start Visual Studio .NET 2003.
2. On the File menu, point to New, and then click Project.
3. Type http://localhost/AppTest, and then click OK.
   
   You may notice the error that is described in the "Symptoms" section of this article.

For more information about application pools, visit the following Microsoft Web site: For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base: