run postflight script for sh201

To fix this error simply open the Terminal application found in the /Applications/Utilties/ folder. You will see a 'console-like' area that you can type in, type the following:

ln -s /System/Library/CoreServices/Installer.app /Applications/Utilities/Installer.app

This creates a symbolic link (shortcut or symlink) to where the file really resides, however the install is looking in a different location, so hit Enter to run the command, and retry the installer.