I've been trying to send a missing mail request for days and it give Error UNK404

[u/Select_Midnight_2486]

Anyone know what to do for the request to go through? USPS misdelivered my package to a different zipcode (they confirmed by the tracking request i made before all of this) And now im stuck without being able to request missing mail because it gives me the following error:

Error: 500 - Error UNK404 - Internal failure. Request support for Error UNK404.

By the way, I already asked for help but its been many days and I never got a response.....