QuickBooks error 1603 generally occurs when there has been an issue in the update process of the QB software and the update installer might have encountered internal damage. The resolution for this issue can be achieved when you reinstall the QBDT extension file in the windows after uninstalling it. To continue with the process, just take a look at these given steps: Press Windows and R key together to open the dialog box for giving the run command Go to control panel> Programs and Features>QuickBooks>Uninstall Download the QB clean extension tool and reinstall QuickBooks using this tool. If the given suggestion doesn’t come out as effective, then you must not waste even a single moment and get in touch with the QuickBooks Customer support number and take the certified help. For more :