VERIFIED SOLUTION i
User receiving the "Connector error - CONNECTOR_ERR_INVALID</SubCode><Reason>Validate enquiry insert. Enquiry No 1. XXXXXXXX is not a valid site code" when trying to send an enquiry update through the confirm connector.
The site code used in the update XML for the enquiry is not valid and does not exist in confirm.
ResolutionUPDATED: October 16, 2017
Check that the right site code has been used for the Enquiry and add into confirm if required or modify the site to the correct site code.