Canada Post is in Development mode or WP DEBUG is on - note, returned services may not match those set in settings. Production mode will not have this problem. To hide these messages, turn off debug mode in the settings.

Canada Post CACHED REQUEST:

<?xml version="1.0" encoding="UTF-8"?>
<mailing-scenario xmlns="http://www.canadapost.ca/ws/ship/rate">
<parcel-characteristics>
	<weight>1.4</weight>
	<dimensions>
		<height>10</height>
		<width>20</width>
		<length>32</length>
	</dimensions>
</parcel-characteristics>
	<origin-postal-code>M6S4A6</origin-postal-code>
	<quote-type>counter</quote-type>
	<destination>
		<domestic>
			<postal-code></postal-code>
		</domestic>
	</destination>
</mailing-scenario>

Canada Post CACHED RESPONSE:

<?xml version="1.0" encoding="UTF-8"?>

<messages xmlns="http://www.canadapost.ca/ws/messages">
<message>
<code>Server</code>
<description>/rs/ship/price: cvc-simple-type 1: element {http://www.canadapost.ca/ws/ship/rate}postal-code of type {http://www.canadapost.ca/ws/ship/rate}PostalCodeType may not be empty</description></message></messages>