QuickBooks error code 1603 generally occurs when the user tries to open or install QuickBooks on a computer. The prominent causes for QuickBooks error 1603 are error with Microsoft .NET framework, Microsoft MSXML, and C++ files are corrupted or damaged, there could be the Windows related issue and an incorrect QuickBooks installation. Here are some quick tips to resolve error 1603 QuickBooks. Step 1 . Download and install the QuickBooks tool hub . Once the installation complete, click finish . Step 2 . Open QuickBooks tool hub on your desktop. Now go to the installation issues and choose QuickBooks install diagnostic tool option. Click the option proceed to start repairing the QuickBooks components and restart your PC. Step 3 . Update your windows to the latest version and restart your computer. Step 4 . Lastly, you will need to manually repair the windows component, .NET framework, and Microsoft MSXML components. Hopefully, these steps resolve the QuickBooks error code 1603.