500 Please wait... 502 Install Windows 508 Windows installation encountered a problem and could not restore your previous version of Windows. For more information, see the Windows installation log files. 509 The upgrade was not successful. Your previous version of Windows is being restored. \n \nDo not restart your computer during this time. 510 The installation was not successful. \nChanges made during the installation process are being undone. \n \nDo not restart your computer during this time. 520 Install Windows 521 This version of Windows could not be installed.\n\nYour previous version of Windows has been restored, and you can continue to use it. Before trying to install this version of Windows again, check online to see if it is compatible with your computer. Go to the Microsoft website (www.microsoft.com) and search for "upgrade advisor".