The "Amend return" link on Turbo Tax says that we are to download the desktop version for the year we want to amend, then have that product open the saved version of the Turbo Tax return we want to amend. When I couldn't get the desktop version of 2020 to recognize or open my file, the Turbo Tax customer service representative discovered that the error code (below) means that you can't use a desktop product to open a return created online. The advice under "Amend your return" does not work. Instead the representative told me to use the desktop version to make a new version, using data from my online created file. This is much more tedious, but WILL solve the problem.
