This article was previously published under Q303207
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Different versions of the MSXML parser may be run in either side-by-side or replace mode.
If you run the MSXML parser in side-by-side mode, newer versions of the parser do not replace older versions on your computer. This installation option does not alter the behavior of XML code that is written for earlier versions of MSXML. For example, different versions of the Microsoft Windows operating system and Microsoft Internet Explorer are released with different versions of MSXML. If they are installing a parser in side-by-side mode, developers who have created solutions that are based on earlier versions of MSXML can download a parser without destabilizing their existing XML code. To address a particular version of the parser, code should include version-dependent ProgIDs.
If you run the MSXML3 SP2 and earlier versions of the parser in replace mode, version-independent ProgIDs point to the newer parser. Xmlinst.exe is usually used to create this effect. Version-independent CLSIDs and ProgIDs reference the newer parser, but version-dependent ProgIDs are still recommended.
MSXML 4.0 does not support version-independent GUIDs and ProgIDs and replace mode upgrades. Xmlinst.exe is designed for MSXML 3.0 and does not work with the current version of MSXML 4.0.
To restore the ability to use version independent PROGIDs, MSXML 4.0 must be unregistered and MSXML 3.0 reregistered. Otherwise,version independent PROGIDs become non-functional.
The following MSXML parsers install in either side-by-side or replace mode:
MSXML 3.0 and earlier install in side-by-side mode.
MSXML 3.0 Service Pack 1 installs in side-by-side mode.
MSXML 3.0 Service Pack 2 will install in replace mode.
MSXML 4.0 will install in side-by-side mode.
If you run the MSXML3 SP2 and earlier versions of the parser in replace mode and then install Msxml.dll, forcing side-by-side mode, you may revert to replace mode by running Xmlinst.exe.
For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
278636 PRB: Application Errors Occur After You Run Xmlinst.exe on Production Servers
To download the latest parser, see the following Microsoft Developer Network (MSDN) Web site: