Mailchimp Headache: Errorsetting Up Multiple Webhooks For One Url Is Not Allowed


So I went to setup mail chimp for use in multiple storefronts and may have used a key twice and went back to change it but now get this and I have no idea what it means or what I need to do to make it work. The API is saved but it won't let me select the mail list.

ErrorSetting up multiple WebHooks for one URL is not allowed.


OK I resolved it - went into mailchimp and deleted the webhook.

but why can't i see the register at checkout checkbox anywhere, where is this supposed to appear?