The error stems from the SSL certificates applied to your domain. It could be that your domain isn't set up correctly (i.e. it had additional "A" records or "AAAA" records), which would be indicated by an "SSL Pending" badge in your store under Online Store/Domains. If that is the case, then please post the URL to your store so I can take a look into what records appear for the domain.
If you're seeing "Connected" and no "SSL Pending" badge, then this could be due to the recent change in SSL certificates that occurred around September 30th. We have a community post here that outlines the steps you can take to troubleshoot this further.
In the event that you do need to contact Shopify Support, then you can do so by logging into your store through the help center, manually typing out your question/issue in the search bar, then selecting "continue" at the bottom of the page that displays the search results.
Trevor | Community Moderator @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog