Thanks for sharing a screenshot of the error message you're seeing. Have you set up shipping rates for your international destinations? If you have, I went through some troubleshooting steps in regards to a similar shipping rate issue on this Community Forums thread. You can go through the steps I listed in that thread to see if that will resolve your issue.
You can also make sure that the products on cart have been marked as a physical product within the product page on your store's Shopify admin, so that they're eligible for shipping. Check out the 'Shipping' section of this help guide for more information on this.
If you still can't pinpoint where the issue is stemming from, our Live Support team can help investigate your shipping settings from our end to further troubleshoot this together with you. To get in touch with our Live Support team, you'll need to login to your store via our Help Center here. Once logged in, select a topic that best fits your query or situation. From there, you'll be taken to a page with a list of relevant support articles, and you can scroll to the bottom of that page to select your preferred contact method with our team. We'll then be able to securely access your store to further assist.
Have you recently checked your shipping rates, or revisited the shipping strategies on your store? Having a solid shipping strategy will help improve the smooth-running of your business operations in general, so if you need help optimizing this aspect of your store, I've curated a few resources you can take a look at. Feel free to have a good read of them below:
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