ASP.NET 1.0 is supported only in IIS 5.0 isolation mode in IIS 6.0

The Microsoft .NET Framework supports side-by-side execution of multiple versions of ASP.NET on the same computer. Currently, there are two versions of ASP.NET, version 1.0 and version 1.1.

You can run Internet Information Services (IIS) 6.0 in one of two possible modes on Microsoft Windows Server 2003, IIS 5.0 isolation mode and Worker Process isolation mode. ASP.NET version 1.1 is supported in both modes of IIS 6.0. However, ASP.NET version 1.0 is supported only in IIS 5.0 isolation mode.

By default, Windows Server 2003 includes Microsoft .NET Framework version 1.1 and IIS 6.0. On a computer running Windows Server 2003, you can also install Microsoft .NET Framework 1.0. You can run both versions of ASP.NET on the same computer. This is one of the features of the .NET Framework.

As discussed in the "Summary" section, IIS 6.0 runs in two possible modes. ASP.NET version 1.0 is not supported in IIS 6.0 Worker Process isolation mode. However, you can create an ASP.NET version 1.0 application in Visual Studio .NET 2002 when IIS 6.0 is configured to run in Worker Process isolation mode. When you run the ASP.NET application, you will notice that, instead of using version 1.0 of the .NET Framework, the application uses version 1.1. For more information about how to configure an ASP.NET application for a particular version of the .NET Framework, see "Configuring an ASP.NET Application for an ASP.NET Version" in the "References" section.

Verify the IIS Isolation Mode

The isolation mode is a system setting. All Web applications on the computer run in only one mode. To verify the isolation mode of IIS 6.0, follow these steps:

1. Open Internet Information Services (IIS) Manager:
   1. Click Start, and then click Run.
   2. Type inetmgr, and then click OK.
2. Expand (local computer). Right-click Web Sites, and then click Properties.
3. Click the Service tab.
4. Verify that Run WWW Service in IIS 5.0 isolation mode is selected. If this option is selected, all applications are configured to run in IIS 5.0 isolation mode.

For more information, visit the following Microsoft Web sites: