Error 1721 is a Windows Installer run-time error displayed in the following format:
There is a problem with this Windows Installer packager. A program required for this install to complete could not be run. Contact your support personnel or package vendor. Action: [2]. location: [3], command: [4].
Error 1721 will not always display the Action: [2], location: [3], or command: [4] portions of the error message.