After a day of work with Postman, I have managed to reduce the number of errors down to 1. No idea how to get past it.

Definitely not an authorisation problem. I’ve been making lots of authorised calls.

URI:

POST https://api.ebay.com/sell/account/v1/fulfillment_policy

Body:

{
  "categoryTypes": [
    {
      "name": "ALL_EXCLUDING_MOTORS_VEHICLES"
    }
  ],
  "freightShipping": "false",
  "globalShipping": "false",
  "handlingTime": {
    "unit": "DAY",
    "value": "1"
  },
  "localPickup": "true",
  "marketplaceId": "EBAY_AU",
  "name": "100 grams",
  "shippingOptions": [
    {
      "costType": "CALCULATED",
      "optionType": "DOMESTIC",
      "shippingServices": [
        {
          "shippingCarrierCode": "Australia Post",
          "shippingServiceCode": "AU_Regular"
        }
      ]
    }
  ]
}

Output:

{
    "errors": [
        {
            "errorId": 20403,
            "domain": "API_ACCOUNT",
            "category": "REQUEST",
            "message": "Invalid .",
            "longMessage": "Please select a valid postage service.",
            "inputRefIds": [
                "service"
            ],
            "parameters": [
                {
                    "name": "XPATH",
                    "value": "DomesticItemShippingService[0].shippingService"
                }
            ]
        }
    ]
}

Things I’ve Tried:

• Deleting "shippingOptions": [...] (and everything inside the []s) got rid of the errors and resulted in the successful creation of a new fulfillment policy. However, I wanted to include shipping options in my call.
• shippingCarrierCode doesn’t seem to do anything. I’ve changed it to all sorts of sensible and non sensible things, including deleting it entirely. No impact on the output.
• Changing shippingServiceCode to anything non-standard (eg "shippingServiceCode": "potato") results in getting the exact same error, but twice instead of once. (See below) How can I get the same error twice with only one shipping option?
• Including a domestic and international option, I get the same error twice also. (Same output as below, except the second DomesticItemShippingService[1].shippingService is instead DomesticItemShippingService[0].shippingService)
• Making an international option AND a domestic option, BOTH with silly service names results in 3 errors. (I was expecting 4.)

Code:

{
    "errors": [
        {
            "errorId": 20403,
            "domain": "API_ACCOUNT",
            "category": "REQUEST",
            "message": "Invalid .",
            "longMessage": "Please select a valid postage service.",
            "inputRefIds": [
                "service"
            ],
            "parameters": [
                {
                    "name": "XPATH",
                    "value": "DomesticItemShippingService[0].shippingService"
                }
            ]
        },
        {
            "errorId": 20403,
            "domain": "API_ACCOUNT",
            "category": "REQUEST",
            "message": "Invalid .",
            "longMessage": "Please select a valid postage service.",
            "inputRefIds": [
                "service"
            ],
            "parameters": [
                {
                    "name": "XPATH",
                    "value": "DomesticItemShippingService[1].shippingService"
                }
            ]
        }
    ]
}

What did I do wrong this time?