MSXML 4.0 Legacy Installation

Microsoft Windows XP, Windows Server 2003 and Windows Vista provide side-by-side installation (WinSxS) of shared components (also known as assemblies). WinSxS allows you to install multiple versions of some components on a single computer.

For example, suppose you had the originally released version of MSXML 4.0 installed on your computer when a new service pack version of MSXML 4.0 was released. If you installed the new version in WinSxS mode, it would not replace the earlier version. With this approach, multiple versions of the same component with the same ProgID and GUID can be installed on a computer. Then, a manifest file can be created that tells the operating system which service pack to use for any particular application.

We do not recommend WinSxS installation. Instead, you should validate your application with the latest SP for your required version of MSXML.


It is recommended that you upgrade from earlier versions of MSXML to MSXML 6.0. MSXML 6.0 provides security and performance improvements over earlier MSXML versions.

Background on MSXML 4.0 and Side-by-Side Assembly

When MSXML 4.0 is installed on Microsoft® Windows® XP, it is installed as a shared side-by-side assembly. Side-by-side assemblies are:

  • One or more .dll files packaged together to install and function as a single shared component.

  • Installed by the Windows Installer into the managed assembly store located off of the Windows system root folder.

  • Authored so that multiple versions of the component can run at the same time without impacting each other.

  • Not registered globally on the system, but are globally available to applications that depend on them.

For Windows XP, you specify all dependencies for your compiled applications or components with manifests. Assembly manifests are used with shared dynamic linked libraries. Application manifests are used with executables.

The following topics provide more information about working with manifests and MSXML 4.0 in Windows XP and Windows Server 2003.


  • The WinSxS technology described in this section applies only when you deploy applications that use MSXML 4.0 to computers running Microsoft Windows XP, Windows Server 2003 and Windows Vista. If your deployment involves earlier versions of Microsoft Windows, such as Windows 2000, Windows NT, Windows ME, or Windows 98, disregard the information in this section.