[Sage Accounting API - The request contained parameters that are restricted for Start in United Kingdom (invoice_lines:quantity)]

Hello,

I am suddenly receiving an error when trying to create a n invoice:

Quote

[{"$severity":"error","$dataCode":"InvalidRequest","$message":"The request contained parameters that are restricted for Start in United Kingdom [invoice_lines:quantity]","$source":""}]

Any ideas what I am doing wrong?

I am not aware of any breaking changes published in the API. This wasn't happening yesterday and no changes to my integration code have taken place.

My JSON looks ok:
 

{
   "sales_invoice":{
      "contact_id":"xxx",
      "editable":true,
      "displayed_as":null,
      "$path":null,
      "payments_allocations":null,
      "total_amount":"96",
      "tax_amount":"16",
      "net_amount":"80",
      "status":null,
      "date":"2022-01-01",
      "DueDate":null,
      "currency_id":"GBP",
      "invoice_lines":[
         {
            "description":"blah",
            "ledger_account_id":"xx",
            "unit_price":"120",
            "net_amount":"120",
            "tax_rate_id":"GB_STANDARD",
            "tax_amount":"24",
            "quantity":"1"
         },
         {
            "description":"blah",
            "ledger_account_id":"xx",
            "unit_price":"-40",
            "net_amount":"-40",
            "tax_rate_id":"GB_STANDARD",
            "tax_amount":"-8",
            "quantity":"1"
         }
      ],
      "Paid":false
   }
}

 

Thanks in advance

Paul