Can not install TT 2020 Premier, receive error code 1603. (Windows Installer error). I have TT 2016,17,18,19 installed on this computer. running Windows 10 Home, verson 20H2, windows update current, running as administrator.
Have run the Windows file check program SFC/scannow. Receive same error when installing from CD and from download.
You have to do an update through the initial installer. So basically you need to completely uninstall the program and reinstall it. Make sure everything is closed in Task Manager of your computer, then reinstall it.
This Turbo Tax FAQ will provide troubleshooting steps on this error.