This patch package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer patch package

Error Message

Note:
The content of this article pertains only to ArcGIS versions 9.x. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.

When attempting to install a service pack for ArcGIS Desktop, the following error is encountered:

Error:   
This patch package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer patch package.

Cause

This error is caused by one or more system conflicts.

Solution or Workaround

Follow the steps below to resolve the error.

1. Special characters in directory names containing the service pack file (such as ' ', or `) can prohibit it from running. To avoid this, copy the service pack installation file to the root C: drive, and attempt the installation from that location.
2. Update the latest version of Windows Installer. To update, go to Windows Installer 3.1 Redistributable (v2) for Windows 2000, or Windows Installer 4.5 Redistributable for Windows XP, 2003, Vista and 2008.
3. Install the service pack from the command line. Navigate to Start > Run, and type CMD. Click OK. Type the following command, and press Enter.

msiexec.exe /p C:\ArcGISDesktop9(#)sp(#).msp