This Order was already submitted Error

Hi,

On our website we are selling video digital files. So you add one or a few of these files to your cart and proceed to Checkout.

When at the checkout page and I click on the ‘Place Order’ button, I get the following error message: “There was an error processing your customer info. Please try again, or contact us if you continue to have problems.”

So then I right-click on the page and select ‘Inspect’ to bring up the Chrome Developer Tools. I choose the Network tab. I then click on the latest ‘apollo’ request. When I expand, I get the following error in the Preview tab: “errors: [{code: “DuplicateOrder”, message: “This Order was already submitted”,…}]”.

No matter how many times I try to change the affected order (by using different email addresses, billing addresses, digital items, combinations), I can’t seem to get it right. The same error message(s) keeps showing up.

How do I fix this error?

Thanks and greatly appreciated.