Also possibly:

TNT B1: unable to execute http call: java.net.SocketTimeoutException: Read timed out

no valid response received.

This error message is shown when carrier TNT is temporarily unavailable. Please try to rebook your shipment at a later time (15 to 30 minutes). If the error persists after that time you could try to rebook your shipment with a different carrier (where possible). 

Should the error not be solved in a timely fashion, please check our statuspage for announcements about this event and follow the topic to stay updated about the status of this issue. If this issues is not yet posted on our forums, please submit a ticket at this link so we can contact TNT about this.