We are a team of accounting software experts who can quickly troubleshoot error 1603 QuickBooks desktop. The issue generally occurs when you install the QuickBooks desktop to your computer or while opening it to perform actions. Firstly, you must download and run the QuickBooks tool hub application to fix this error, and if you're not able to fix it, then try updating your windows as per the latest version. After that, you can try to repair the specific Windows components by yourself, such as repairing Microsoft .NET framework or repairing Microsoft MSXML. However, sometimes using all these tips requires you to be an IT professional or a confident Windows or Microsoft user. In that case, you can learn under the guidance of experts and fix the error 1603 QuickBooks by yourself.