I am getting an error message, just not in the same part of the procedure.  Before the error message showed right at the beginning and wouldn't let me attach the xml file.  Now, with the T5018, I get all the way to submit and then this is the error message.

*Before proceeding, please acknowledge the following statement(s):

(Check Box) I want to proceed without correcting the errors

Please correct the following errors: To continue, you must view the error report.

The error report says 'Filer account number is missing or invalid for this type of return'

I am not sure where the account number would be missing or invalid

I was using the Information Returns portal to upload this file, because the extension on the account number is RZ0001