Hello,
I just tested it on my end and it worked fine, are you only having that issue when saving the configuration of the canada post shipping plugin ?
Did you apply some modifications on the code of the plugin ?
If that's not the case, can you send us a temporary access to your back-end so that we can directly test and debug it on your website ? You can send it through our contact form by specifying a link to that thread in your message :
www.hikashop.com/support/contact-us.html
Thank you !
Kind regards,
Mohamed.