The business accounting tool QuickBooks makes it easier to manage payroll, books, and other financial management tasks. When there is an issue with your computer’s network connection or firewall configuration, the error 1603 manifests. Error 1603 Quickbooks Checking your internet connection, restarting QuickBooks, and, if necessary, updating your QuickBooks software from the help menu can usually resolve the majority of minor QuickBooks difficulties. Verifying that your QuickBooks software is current and then checking your computer’s settings for issues are the best ways to resolve this issue.