I got this error when after adding my NETFILE access code "If you see an error, it may be due to a CRA issue affecting all CRA certified tax software across Canada. We’re working with the CRA to get this resolved. Please visit the TurboTax Canada blog for the list of applicable errors."
Please double check that your NETFILE Access Code (NAC) is correct and has all 8 characters. You can also try submitting your return without the NAC. The NAC is optional and not required to file your return.
