Having lost my *tax2017 file because backup didn't recognize the odd file type, I tried to use my pdf file created by TurboTax 2017 as input to turbotax 2018, but it failed saying the input file was too large. (It did contain all the worksheets and schedules.) I only got boilerplate from TurboTax support which didn't address the "too large" problem. So I fired up CutePDF and exported just the 3 pages of 1040 and it accepted that pdf file.
