Examine the xml file used for the import. Find the <Device model_handle=....> tag for the model handle displayed in the error. In the above example, the following is seen in the xml file for that model handle:
<Device model_handle="0x1c96f6" > <Port identifier_name="portID" identifier_value="" model_handle="0x1c9795" /></Device>
The above entry is missing the network_address parameter. It should look like the following:
<Device network_address="1.2.3.4" model_handle="0x1c96f6" > <Port identifier_name="portID" identifier_value="10140" model_handle="0x1c9795" /></Device>
The cause of the missing network_address parameter is the associated model in the database where the Modeling Gateway export was run does not have the Network_Address attribute id 0x12d75 populated.