QuickBooks is the world-renowned accounting software and has become a boon for accounting professionals and business owners. To resolve any expected or unexpected error, the developers have designed the QuickBooks install diagnostic tool. It ensures that the QuickBooks installation is completed without delay and helps resolve issues with the .NET framework, MSXML, and C++ errors. Some other issues that QuickBooks diagnostic tool fixes are QuickBooks error code 1603, QuickBooks error 1935, QuickBooks error 1904. First, you will need to download the diagnostic tool from the QuickBooks website and install it using predetermined steps. Once the installation completes, you can check the firewall status, test the connectivity or reinstall in a selective startup mode.