I attempted to file an extension today as a Self Prepared (XSP) return and the transmission rejected because the eFile failed to include an EFIN PIN. I've been using ProSeries Professional for years and never encountered this issue before. I tried unsuccessfully to enter my own EFIN PIN (since I'm also the ERO) into the 4868 EF Information Worksheet.

Thanks for the suggestion LiebeNigro. I did nearly the same thing...on the Form 4868 EF Information Worksheet, I checked the box "Automatically generate a PIN equal to last 5 digits of client's SSN". My extension transmitted without fail. Problem solved.