During my installation of TurboTax Deluxe 2019 from an Amazon.com download, I receive the following Error Code: 1921. I have attempted the installation twice.

[Anonymous]

you can try this first

Close all programs (including TurboTax), restart your computer, reopen TurboTax, and try updating again.

If that didn't work, close TurboTax and try this:

1. In Control Panel, open Administrative Tools and select Services.
2. Right-click Intuit Update Service and choose Stop.
3. Reopen TurboTax and try updating again.

if this doen't work 

what is your operating system?

or contact TT support

the problem may be with Microsoft's .net framework which is needed for the desktop app to run.  It's installed when you install TT.  however if it was already installed it may be corrupted