Updating windows receive an 646 error
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Solution: From the sounds of things, a Word setting has been changed.
My team was recently working on our installer when we ran into a return code from one of our pre-requisites (specifically the Visual C 2015 Runtime).
From the logs, we found the error code was 0x80070666 and the return code was 0x666 (a newer version of the runtime was installed).
If Windows Installer determines a product may be incompatible with the current operating system, it displays a dialog box informing the user and asking whether to try to install anyway.
This error code is returned if the user chooses not to try the installation.