As a response to a transaction attempt, you may sometimes find errors that start with "unknown order", e.g. "unknown order/1/s/". These are usually logged in the "Error logs" of your PostFinance account.
"Unknown order" errors can be explained by a problem in your integration (e.g. with e-Commerce or DirectLink) and/or wrong or missing configuration in your account's Technical information page.
The "unknown order" errors, among others, are explained on the Possible errors page.