Invalid update options for items on a trialing subscription

{
  "error": {
    "type": "request_error",
    "code": "subscription_trialing_items_update_invalid_options",
    "detail": "You can't add or remove items for a subscription in trial, and you must use `do_not_bill` as the `proration_billing_mode` when updating quantities of existing items.",
    "documentation_url": "https://developer.paddle.com/errors/subscriptions/subscription_trialing_items_update_invalid_options"
  },
  "meta": {
    "request_id": "00000000-0000-0000-0000-000000000000"
  }
}

Details

Status code

400

Error code

subscription_trialing_items_update_invalid_options

Error message

You can't add or remove items for a subscription in trial, and you must use `do_not_bill` as the `proration_billing_mode` when updating quantities of existing items.

Common causes

• You're changing item quantities on a trialing subscription without using proration_billing_mode: do_not_bill.
• You're adding an item to a trialing subscription.
• You're removing an item from a trialing subscription.

Troubleshooting

• To change quantities during a trial, use proration_billing_mode: do_not_bill.
• Wait until the trial ends before adding or removing items.