Our customs broker changed an XML prefix and every shipment stayed on the dock

Our customs broker confirms each export declaration by sending an XML message with a status and a reference. In October they upgraded their messaging platform over a weekend. On Monday every shipment leaving our warehouse sat at awaiting clearance. The trucks were loaded, and the broker insisted, correctly, that every declaration had cleared. Their messages had arrived with the same content. What changed was how the XML was written. The old platform declared the broker's namespace with the prefix cus and wrote cus:Status. The new one declared the same namespace URI with the prefix ns2 and wrote ns2:Status. To any XML parser those are the same element. To our reader they were not, because six years earlier someone had written it with an XPath expression containing the literal text cus:Status, plus a fallback regular expression looking for the same string. Neither matched. The reader found no status, and our model treated a missing status as pending, which is a sensible default for a de