The full error came in as:
Error Message:
RequestId:d558ebad-c504-4873-897f-47c97dc32694, Exception:System.Data.SqlClient.SqlException (0x80131904): String or binary data would be truncated.
The statement has been terminated.
User stated it was when he was trying to create a shipment. I looked in full story and it was due to the user copying the item title and trying to use that as the shipment name.
Shipment names have 40 character maximum so check this for the cause if you get this particular error.
This can also be due to entering more units per case pack than Amazon allows. A single case can not contain more than 150 units per Amazon.