I've been using the standard paypal checkout plugin for woocommerce as a checkout method, however, I'm looking to speed things up by using the WooCommerce Express Checkout Gateway. Although orders go through fine on the standard plugin, express creates the following error: Paypal error (10004). I've looked up the error and it looks like it's very general: "An invalid argument was used" Link: https://www.paypal-knowledge.com/infocenter/index?page=content&id=FAQ1122&actp=LIST In terms of setting up the plugin I authorised the plugin by using the auto configure button which connected to my PayPal account and automatically filled in the Live API Username, Password and Signature. The only thing it hasn't done is create a 'Live API Certificate' but it doesn't say if this is required or not. Nor do I know if this is creating the issue. What next steps should I be taking to get this plugin running smoothly?
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