my issue was that after Start New Return, TT2021 couldn't find any other TT files. on my Mac I did a Get Info on my TT2020 file and saw that it had a hidden .ta...
I am a Mac user. my 2020 return was clearly in my Documents folder but TT2020 had not appended .tax2020 to the name of the file. I did that and then TT2021 foun...
