Why paper file?

I've been filing with TurboTax for 15 years or so. I rarely have an issue and they've helped me when I needed it. I usually pay through bank debit when I owe. 

This year I was following the usual routine, I e filed and okayed the bank debit.

Then, and I almost missed it, there was a screen that said I STILL needed to paper file or my return would not be complete. What? Why? Has this always been the case and I've skated all these years? I've never paper filed when I efiled and paid electronically?