WooCommerce - 404 Error for Cart, Checkout and other WooCommerce pages [resolved]
I finally found a cure for this (the 404 error not the whirly icon) and don't understand why but it seems to work ... for me anyway.
I created a new page eg: called "Orders"
I then edited the "Checkout" page and changed the parent from "Product" to "my new "Orders" page. Did the same for all other children of the "Product" page (Transactions and Your Account).
Go to your home page, refresh and click checkout and it should all work!