Use this guide when API Type → REST API is selected in WooCommerce → Settings → Shipping → Canada Post Live Rates.
Start by checking that API Key and API Secret belong to the same Production application and that the app has access to Rating. See How to get the REST API Key and API Secret?
The connection check fails
Authentication errors or HTTP 401
Check that the credentials are complete and match the application. Do not enter Legacy API credentials, a Canada Post website password, an Octolize subscription key, or an access token in these fields. If the application credentials were reset, update the saved values in WooCommerce.
The plugin obtains tokens automatically. An expired or invalid token can cause a 401 response; Canada Post explains this in its Authentication guide.
Access denied or HTTP 403
Check the application’s access to the Rating product and its account status in the Developer Portal. Review the actual error text. If access still fails with the correct credentials, contact Canada Post support with the app and product details.
Do not assume that a REST 403 is the same as the Legacy AA004 error. The Rating specification lists REST authorization responses separately.
A timeout, transport error, or HTTP 5xx
Try again and check whether your hosting provider allows outgoing HTTPS connections to api.canadapost-postescanada.ca. If the error persists, provide its exact text and time to support. A carrier service error may be temporary; it does not by itself mean that the credentials need to be replaced. REST service errors are described in the Rating specification.
The status is OK, but the cart has no rates
The REST connection check uses a sample Counter shipment. An actual cart has different addresses, parcels, and potentially Commercial account details.
Check that:
- A Canada Post Live Rates method is enabled in the shipping zone matching the delivery address.
- The cart contains a physical product and the destination details are valid.
- The origin is a valid Canadian shipping address, including any Custom Origin configured globally or in a PRO method.
- Parcel weight is positive and the dimensions and weight fit the service limits.
- The services selected in the method are available for the route and every parcel.
- The method’s Quote Type and global account details match the rates you intend to request.
Enable Debug Mode while signed in as an Administrator or Shop Manager and inspect the actual request and response.
Commercial rates fail, but Counter rates work
Check Customer Number in the global settings. Commercial quotes require it. For contract customers, also enter the correct Contract ID. Solutions for Small Business members and business users without a commercial contract should leave Contract ID empty. See Canada Post’s Rating field definitions.
Preserve leading zeroes. Confirm that the customer account and contract are the ones you intend to use. A successful Counter quote does not validate these account details.
Package weight must be greater than 0 kg
Set positive product weights or a positive Default weight [kg] in the shipping method. If the calculated weight rounds to zero, the plugin tries the default. That value must also remain positive when rounded to three decimal places in kilograms.
For PRO packing, review the weight of each resulting parcel.
The returned price is unexpected
Compare the same service, account, quote type, parcel details, origin, destination, insurance, and tax treatment. Check PRO handling fees, additional cost rules, and whether the cart is packed into more than one parcel.
See How to Fix Canada Post Shipping Rates showing Too high or Too low?.
Information to include when contacting support
Provide the plugin version, selected API Type, exact error message, time of the failed request, Quote Type, relevant method settings, and shipment details needed to reproduce the problem. If using Debug Mode, include the request and response after removing credentials, access tokens, and personal data.
For Commercial issues, confirm whether the account is a contract account or a Solutions for Small Business account. Do not send your API Secret.