Error: #10500 Service Temporarily Unavailable
This error is due to some issue with UPS servers. This means the request reached the UPS servers, but their system encountered an unexpected condition or temporary failure preventing it from fulfilling the request.
Because it is a server-side glitch, wait 5 to 10 minutes and try the request again.
Alternatively, check UPS Server status for any reported outages. Often with temporary issues they will not be acknowledged.