Originally Posted by
Larch2017
Thanks!
I tried again and it works. Turned out, the address is required although it says [optional] on the form. And you are right, the address has to be exactly the format it likes.
Can only say it is a poorly designed form with confusing error message.
If you're just signing up for an Aeroplan number, I'm guessing you're fairly new to AC. So, welcome. AC's service in the air is generally fairly good, but anything to do with AC or Aeroplan's IT is an embarrassment compared to what the US3 offer.