I have encountered this issue in the past, and generally it was just an issue of adjusting the Geo Zones and calling it a day.
I have 5 other sites that are up and running without issue, but for some reason, no modification to Geo Zone / Shipping Config will get past this error.
I have verified that my client is on USPS production server, so I know that that is not the issue. I am not seeing ANYTHING being logged into the error log what so ever.
I have gone so far as to drop the DB, wipe the server and completely rebuild their store thinking maybe some file corruption had occurred. NO LUCK!
Any advice would be welcome at this point.
I have the USPS configured in the following manner -
Using all Domestic Services
Size - Regular
Machinable - Yes
Dimensions - 10x10x10
Girth - 10
Display Delivery Time - No
Display Delivery Weight - No
Weight Class - Pound
Tax Class - (I have tried both Taxable Goods and NONE)
Geo Zones - All Zones
Status - Enabled
Debug Mode - Enabled
Geo Zones I have configured in the following manner
TN STATE = Tennessee
TN STATE = 7%