Hi Josephzhang and nwplumbing,
Currently, we haven't received any reports about issues downloading ABA files. Since you've confirmed that none of the details have been changed, try clearing your browser's cache first to see if that helps.
If that doesn't do the trick, start by selecting or deselecting one contact at a time and press the "Download bank file" button. If you get an error again, it means that the payment details of the selected contact(s) need checking. If you see the confirmation warning window, then those selected contacts are all good! Keep repeating this until you find which contacts are causing the error. Hope this helps!
Cheers,
Princess