If you encounter this code, it is rarely something that can be fixed through the website or app. You must take direct action: Contact Customer Service : The sender should call the Western Union Error Resolution 1-800-325-6000 to discuss the block. Verify the Relationship
Alternatively, you might be on the receiving end. The sender provides you with a 10-digit MTCN (Money Transfer Control Number), but when you visit an agent location or try to pick up the money online, the system rejects the transaction with "U0407 – Invalid or Expired Reference." U0407 Western Union Code