Microsoft KB Archive/225043

{|
 * width="100%"|

INFO: Installing and Replacing DLLs During Setup

 * }

Q225043

This article discusses a Beta release of a Microsoft product. The information in this article is provided as-is and is subject to change without notice.

No formal product support is available from Microsoft for this Beta product. For information about obtaining support for a Beta release, please see the documentation included with the Beta product files, or check the Web location from which you downloaded the release.

-

The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), used with:
 * the operating system: Microsoft Windows 2000

-

SUMMARY
If your Setup program installs DLLs, check each DLL to make sure that it does not already exist in the target folder. If the DLL already exists, check the version of the DLL that you are replacing to make sure that you are not copying over a newer version.

Never attempt to replace a System DLL. Windows 2000 prevents applications from replacing any System files.

MORE INFORMATION
When you are writing a Setup program you determine where your files should be installed, identify conflicts with currently installed files, and perform the installation process. A conflict occurs when a file that your Setup program will copy is an older version of an existing file. If you downgrade an existing DLL, other applications may not work properly. Always check the file version, and only replace an existing DLL if it is older than the one your Setup program will copy.

See "About File Installation" in the Platform SDK documentation for information on how to compare file versions.

It is not a good idea to replace System files with an application Setup program. Windows 2000 System File Protection prevents applications from overwriting System files. If your application tries to replace System files, it will not work on Windows 2000.