Looks like I may have found the answer on the website below. https://www.canada.ca/en/revenue-agency/services/e-services/e-services-individuals/netfile-overview/eligibility.html It sounds like Netfile is not (or no longer) open for income tax returns for 2014 or earlier.... paper return it is.
I'm getting the error below when using UFILE 2014 to submit a 2014 tax return (I know... very late). "The Canada Revenue Agency was unable to process your return. The transmission contains invalid or missing data: Tax year" This sounds like a very basic field that is not being transmitted with the file to CRA?! I did not have to enter the tax year anywhere during the interview phase, nor did I get any other errors.