ERROR: No customer id was created.
This is an internal add-on error, not from Stripe's API. The error is likely either:
- No user is associated with the client for the invoice.
- The user associated with the client (and tied to the invoice) was used during test payments and it now has an invalid customer id for live.
In summary: make sure all of your invoices not only have a client associated but a user, otherwise the customer profile within Stripe cannot be created; also, do not use the same users/clients when testing.