This error can occur when updating the messenger, the installation process starts normally, but when I got close to 100% or uninstall again: "Close all other programs and try again. It seems as if another program is preventing the operation of the installer . hr: 0x80070643. "
Solution: Download Microsoft-Fix-it This run, the process ends when he says: "This Has Been Microsoft Fix it processed." Then try to upgrade. According to the Microsoft Support This generic error indicates that an error was encountered Windows Installer.