Ditto what TLhM said. This is a Microsoft installer issue. I have windows 8 64 bit and had the same error when attempting to update. Went to the Microsoft website and ran their "Fix it" application, told it I was having problems uninstalling 4.6.3, when it completed, I ran the latest Evernote Installer and it ran quickly and correctly. About now shows V18.104.22.16836 installed, the windows uninstaller shows only this version of Evernote installed and my syncing works correctly. Hopefully, this will work for the rest of you as well. Good Luck!