We tried, but couldn’t get any info from your file

Doing the Free Online Version this year and trying to transfer last years tax info from PC version Deluxe. The saved file is PDF and the file will load into the desktop Deluxe Version 2021 with no issues. Why am i getting this error: 

We tried, but couldn’t get any info from your file
Make sure your PDF contains last year’s return before trying again.
2020 McManus T Form 1040 Individual Tax Return_Records.pdf