Sometimes QuickBooks update error 1603 occurs while installing or updating QuickBooks, which hampers the smooth functioning of QB desktop. You can follow these quick fixes to resolve error 1603, firstly download and install the QBInstallTool.exe file and then save it into your desktop. Now run this tool and check if the problem is solved or not! Follow the second method to fix this error, uninstall the QuickBooks desktop from the program and feature menu and click Change or Uninstall. Then reinstall the updated version from QuickBooks website, follow these steps to resolve QuickBooks update error 1603.