Also possible:

An error occurred: Http failure response for https://api.transsmart.com/v2/prints/(ACCOUNTCODE)?reference=(SHIPMENT REFERENCE): 500 OK

This error message will be shown in our my.transsmart.com portal in the following situations:

- you have tried printing a label for a shipment that has already reached status DONE. The label is no longer in our database, so you cannot retrieve it anymore.  If you need the label still, try downloading it through the Manage Shipments tab by clicking the following button in front of the specific shipment:


- you have tried printing a label for a shipment that is currently in status ERR = error. Most commonly, we see that customers try to book and print a shipment and receive this error thinking the cause is a printing issue. Most of the time however the issue is the error thrown during booking (the booking phase is always handled before the printing phase). 

- you have tried printing a label for a shipment without properly configuring the Smartprint client first. See the following link for more information on how to operate the Smartprint program succesfully.

https://helpcenter.nshift.com/hc/en-us/articles/4408089758738-Installing-the-SmartPrint-Client

- there is conflicting configuration in place for your account. Possibly PDF and ZPL label generation and retrieval combined with user-based rights are causing this error. Contact our support (see below) for assistance in this matter. 

Should neither of these be the cause of your issue, please create a ticket through this link.