The Microsoft WindowsInstaller is an application installation and configuration service. WindowsInstaller-KB893803-v2-x86.exe is the redistributable package for installing or upgrading Windows Installer. This revised package replaces the previously released redistributable package named "WindowsInstaller-KB893803-x86.exe" and addresses the issue discussed in KB Article 898628: Windows Installer fails silently after you upgrade to Windows Installer 3.1.
For more information about the Windows Installer 3.1 redistributable, see KB Article 893803: Windows Installer 3.1 is now available.
Note for users of previous versions of the Windows Installer: The new Windows Installer Redistributable follows a new naming convention that contains a Knowledge Base reference so it is easier to identify which version of the Windows Installer will be installed. The previous naming convention, INSTMSI.EXE, will no longer be used.
