Maybe I was just lucky, but I may have found a solution for this problem. I had the same issue except I wanted to open my 2020 return. I had an issue with my computer and they wiped it clean so I lost all my TT installation. I had the disk and key and reinstalled 2020. I tried opening the return and got the 102345 error. After much troubleshooting, I saw that there were three files with the same name but different extensions. So, I change one digit in the name on the file that was the biggest and tried the process over. Low and behold, it loaded without issue except that the program couldn't find my state downlead, which I then had to downloaded for 2020, and all was good! I was then able to fully research what I did back then. Hopefully, this helps others!
Jeff
