I just encountered the same error of my 2016 TurboTax file (Mac download) being rejected by TurboTax online. The tech support agent I spoke to claimed that it's because the version of TurboTax 2016 that I used was downloaded onto my father's computer using his TurboTax account, and the same user account has to be used for both the previous year and the current year. I have never in my life encountered a software that cares where a locally installed software came from when it comes to ownership of the files it generates. Absolutely ridiculous.
