If you upgrade from Windows 7 to windows 10 and the machine just sits there at zero percent there is a simple cure that you will see immediately. While the update window is on the desktop go to the 'Control Panel', then 'Administrative Tools' then to 'Services'. Now go down to 'Windows update' and set it to "Disabled". Immediately the installation will continue. If you had set Windows 7 updates to 'Disabled' before you started the installation you would have save lots of hours. This worked for me.