Are you adding these packages for use with a specific carrier, or just under Settings > Shipping > Packages as a custom package? I was able to add the 21x10x8cm package under Settings > Shipping > Packages > Add package > Custom packaging as a "Soft package", and the 23x10x9cm package as a "Box" in my test store.
If you can clarify where you're adding these packages and even share a screenshot of the error message, I'll be able to investigate further and can check in with our Shipping team for advice if necessary.
I don't see your screenshot here, but I'll send you an email so that you can send it in a reply. That way, we won't need to worry about sharing your store information publicly in the Community here. I'll also be able to authenticate your account and share it with our Shipping team in case they need to take a closer look. Looking forward to getting this sorted out!
I cannot see the error message that you are getting. I am assuming, the error was related to the size of the package not sufficient to accommodate the product. If that is the case, kindly make sure that the length, breadth and height of the package is able to accommodate the product. Dimensions can be a little confusing. For example a box with 23 x 10 x 9 cm cannot take in an item that is 11 x 4 x 15. Hence you need to slightly be careful. Other than that, adding packages should not be a problem in Shopify. Finally, if you are looking at a way to handle automatic packaging based on product dimensions, you can opt for the Multi Carrier Shipping label app.
I am having the same issue with Canada Post saying the package is too small. I dont know how to fix it and I can't keep sending big boxes for little items. I've attached a photo .
Thanks for sharing this screenshot. It's really helpful to see the dimensions you've entered.
It looks like this package would be shipping from Canada to the United States, is that correct? Through Shopify Shipping, the minimum package size for purchasing Canada Post shipping labels that ship to the US or internationally is 14 x 9 x 0.1 cm (5.51 x 3.55 x 0.04 in.). Packages shipping within Canada need to be at least 10 x 7 x 0.1 cm.
I absolutely understand not wanting to use a larger package just to meet these requirements. For the time being, Shopify Shipping cannot work around the minimum package sizes for printing labels with Canada Post. In order to use a smaller package, labels will need to be purchased directly from Canada Post instead of in the admin.