Variant Does Not Exist Error
If you delete a product or variant in Shopify that customers are still subscribed to, it will cause the error saying: Variant removed from Shopify. This could also happen if you change your variant options. Existing customers that point to the old variant_id will not be able to have orders generated, and we don't prep the future orders either since it needs the variant_id for things like shipping rates, SKU, and more.
Simply click this link to view the list of all the variants that are currently missing in the Broken Active section.
Find the customers with the error and on each one, click Fix.
If the product exists, then it preselects it, otherwise, you will select the new variant to point it to. Doing this will automatically resolve all customers who have those variants in their subscriptions.