I wanted to reinstall the TurboTax Federal and State programs for 2018. I was able to install the Federal program from my disk. When I opened my 2018 return, TurboTax said that it needed to download the State program, as I had used the Deluxe version. However, it ran into "a slight problem, and to try back later". When multiple attempts over several days failed, I was able to reach a customer service person, who informed me that TurboTax only supports their programs for 3 years, and so the state program was not available.
That is an understandable policy, and one that I later saw written somewhere in their website. BTW, this means that the information provided in Solved: Archiving program files for future reinstallation (intuit.com) regarding being able to download older state programs is not correct. Out of curiosity, I tried installing the federal programs for 2019, 2020, 2021 and 2022, and was also able to download the state programs for those years, but not for 2018.
What this also means is that I cannot use the 2018 disk to even work on the federal return, as TurboTax won't go further than looking, and failing to download, the state return.
My question is regarding future use of TurboTax, and avoiding a similar problem. I want to be able to download a copy of the state program executable for each of the past years while it is available, so, if in 2024, say, I want to open a 2020 return, I can install both the federal and the state programs. How do I download the state program for each year so I will have it in an executable form (like I have the Federal on disk), and how do I install it once I have installed the Federal?