When this error message happens it typically means that the product(s) in your cart are having trouble making a clear path to a shipping rate. There’s a few reasons this could be happening. To start troubleshooting I would recommend the following:
Ensure all of your products are in shipping profiles. You can find your shipping profiles by going to Settings > Shipping and delivery. You can also read more about shipping profiles on this page.
Confirm that you’ve set up shipping zones and shipping rates correctly for the locations where your inventory is hosted. You can find your shipping rates by going to Settings > Shipping and delivery and clicking Manage next to the shipping profile. Once there, make sure you see compatible shipping zones and rates for each location that has inventory you need to ship. You can read more about shipping zones here and you can read more about shipping rates on this page.
If you are using price based shipping rates, confirm that your rates cover all order total possibilities. For example, if you only have one rate set up as “free shipping on orders $100 and up”, but you are trying to check out with an order less than $100, there would be no rates to show and you would receive that error message.
Confirm that the product(s) being purchased are set up properly to inform which shipping rates should apply. For example, on the product detail page double check that the setting This is a physical product is enabled for all products that need to be shipped. If you are using weight-based shipping rates or calculated shipping rates you will also want to double check that the items being purchased have a weight assigned.
Make sure that your products and variants have inventory at the locations you are shipping from. You can find this by going to Products and clicking on the product you want to view. Under the Inventory section you will see a list of the locations you have and the amount of inventory you have at each location. You can also read more about assigning inventory to locations on this page.