DHL shipments cannot be created.
The system.log shows this error message:
Warning: Invalid argument supplied for foreach()
in ... lib/Dhl/Versenden/Bcs/Api/Webservice/Parser/Soap/CreateShipmentOrder.php
The reason for the above error is usually a login problem, i.e. the DHL credentials are not working correctly.
It is possible that the password for the DHL user has expired, see also this article.
Please follow the instructions in this article to resolve the problem.