After successfully filing 4 returns, these last two (joint filing) both kick back a xml2020 error. From reading online it sounds like maybe an illegal character is some name/address/entry somewhere but I can't find anything wrong when looking over the forms. Also, we imported last years return so all those entries will have carried in and last year there was no issue. I have restarted the computer to no effect. Do we really have to mail in our returns?