Quantity field missing for new items in subscription update

{
  "error": {
    "type": "request_error",
    "code": "subscription_quantity_missing_for_new_items",
    "detail": "the quantity field must be included for each new item to be added",
    "documentation_url": "https://developer.paddle.com/errors/subscriptions/subscription_quantity_missing_for_new_items"
  },
  "meta": {
    "request_id": "00000000-0000-0000-0000-000000000000"
  }
}

Details

Status code

400

Error code

subscription_quantity_missing_for_new_items

Error message

the quantity field must be included for each new item to be added

Common causes

• One or more of the new items that you're trying to add doesn't contain a quantity field.

Troubleshooting

• Ensure a quantity field is included with each new item to be added.