In Windows Vista and in Windows Server 2008, software updates use a new technology to install .msu files. To manually install .msu files in a Windows Vista or Windows Server 2008 environment, you must have the Wusa.exe tool installed. However, this tool returns a “1 (S_FALSE)” error code when either of the following conditions is true:
- You try to install a software update that is already installed on the computer.
- You try to install a software update that does not apply to the computer.