Error when customer tries to see invoice. Link broken

Not found, error 404
The page you are looking for no longer exists. Perhaps you can return back to the site’s homepage and see if you can find what you are looking for. Or, you can try finding it by using the search form below.

The above is what the customer sees when he clicks on the link to view his invoice. This makes the plugin useless if customers can not see their invoice.

https://www.ads-software.com/plugins/wp-invoice/