This article discusses how to switch between the 32-bit version of Microsoft ASP.NET 1.1 and both the 32-bit version and the 64-bit version of ASP.NET 2.0 on a 64-bit version of Microsoft Windows.

When you install both versions of ASP.NET, you may receive error messages if you do not perform steps to enable each ASP.NET environment to run in Microsoft Internet Information Services (IIS) 6.0. For example, when ASP.NET is not set up correctly, you may receive the following error message from a Web page: Error messages that are similar to the following may be logged in the Application log.

Event ID: 2268
Raw Event ID : 2268
Record Nr. : 3746
Source: W3SVC-WP
Category: None
Type : Error
Machine : servername
Description:
Could not load all ISAPI filters for site/service. Therefore startup aborted.

Event ID: 2274
Raw Event ID : 2274
Record Nr. : 3745
Source: W3SVC-WP
Category: None
Type : Error
Machine : servername
Description:
ISAPI Filter 'C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_filter.dll' could not be loaded due to a configuration problem. The current configuration only supports loading images built for a AMD64 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see http://go.microsoft.com/fwlink/?LinkId=29349.

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IIS 6.0 supports both the 32-bit mode and the 64-bit mode. However IIS 6.0 does not support running both modes at the same time on a 64-bit version of Windows. ASP.NET 1.1 runs only in 32-bit mode. ASP.NET 2.0 runs in 32-bit mode or in 64-bit mode. Therefore, if you want to run ASP.NET 1.1 and ASP.NET 2.0 at the same time, you must run IIS in 32-bit mode.

Note If you have Microsoft Exchange Server 2007 installed on the computer, use the instructions for ASP.NET 2.0, 64-bit version.

Before you can switch between the different versions of ASP.NET, visit the following Microsoft Developer Network (MSDN) Web site to download and install both the .NET Framework 1.1 and the .NET Framework 2.0: For example, if you are running Microsoft Windows x64 Edition, download the following two redistributable packages:

•	The .NET Framework Version 2.0 Redistributable Package x64 (64 Bit)
•	The .NET Framework Version 1.1 Redistributable

After you install the redistributable packages, you can switch between the different versions of ASP.NET. To do this, follow these steps for each ASP.NET version:

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ASP.NET 1.1, 32-bit version

To run the 32-bit version of ASP.NET 1.1, follow these steps:

1.	Click Start, click Run, type cmd, and then click OK.
2.	Type the following command to enable the 32-bit mode: cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 1
3.	Type the following command to install the version of ASP.NET 1.1 and to install the script maps at the IIS root and under: %SYSTEMROOT%\Microsoft.NET\Framework\v1.1.4322\aspnet_regiis.exe -i
4.	Make sure that the status of ASP.NET version 1.1.4322 is set to Allowed in the Web service extension list in Internet Information Services Manager.

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ASP.NET 2.0, 32-bit version

To run the 32-bit version of ASP.NET 2.0, follow these steps:

1.	Click Start, click Run, type cmd, and then click OK.
2.	Type the following command to enable the 32-bit mode: cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 1
3.	Type the following command to install the version of ASP.NET 2.0 (32-bit) and to install the script maps at the IIS root and under: %SYSTEMROOT%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i
4.	Make sure that the status of ASP.NET version 2.0.50727 (32-bit) is set to Allowed in the Web service extension list in Internet Information Services Manager.

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ASP.NET 2.0, 64-bit version

To run the 64-bit version of ASP.NET 2.0, follow these steps:

1.	Click Start, click Run, type cmd, and then click OK.
2.	Type the following command to disable the 32-bit mode: cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 0
3.	Type the following command to install the version of ASP.NET 2.0 and to install the script maps at the IIS root and under: %SYSTEMROOT%\Microsoft.NET\Framework64\v2.0.50727\aspnet_regiis.exe -i
4.	Make sure that the status of ASP.NET version 2.0.50727 is set to Allowed in the Web service extension list in Internet Information Services Manager.

Note The build version of ASP.NET 2.0 may differ depending on what the currently released build version is. These steps are for build version 2.0.50727.

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Technical support for x64-based versions of Microsoft Windows

If your hardware came with a Microsoft Windows x64 edition already installed, your hardware manufacturer provides technical support and assistance for the Windows x64 edition. In this case, your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation by using unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with a Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware. If you purchased a Windows x64 edition such as a Microsoft Windows Server 2003 x64 edition separately, contact Microsoft for technical support.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site: For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site:

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For more information about 64-bit versions of Windows and the 64-bit version of the .NET Framework, visit the following Microsoft Developer Network (MSDN) Web sites:

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