antiwork/gumroad · error · Purchase::PurchaseInvalid

Gift purchases cannot be on installment plans.

Error message

Gift purchases cannot be on installment plans.

What it means

Raised when a gift purchase also requests installment payments (params[:pay_in_installments] truthy). Installment plans charge the buyer over time while gifts settle immediately against a recipient-side purchase, so the two options are mutually exclusive in create_gift.

Solutions

  1. Turn off installment payments (pay in full) to gift the product.
  2. Keep installments and remove the gift params to buy for yourself.
  3. Integrators: make the gift and installment options mutually exclusive in the checkout UI.

Example fix

# before: both flags sent together
params[:gift] = { giftee_email: 'friend@example.com' }
params[:pay_in_installments] = true

# after: gift purchases pay in full
params[:pay_in_installments] = false if params[:gift].present?
Defensive patterns

Strategy: validation

Validate before calling

params[:pay_in_installments] = false if params[:gift].present?

Try / catch

begin
  Purchase::CreateService.new(product:, params:, buyer:).perform
rescue Purchase::PurchaseInvalid => e
  # ask the buyer to pick one: full-price gift or non-gift installment purchase
  render_checkout_error(e.message) if e.message == 'Gift purchases cannot be on installment plans.'
end

Prevention

When it happens

Trigger: Gift params present (is_gift?) and params[:pay_in_installments] truthy in the same checkout request.

Common situations: Buyer toggled installment payments before switching the checkout to a gift and the client kept the flag; integrations that send pay_in_installments unconditionally.

Related errors

AI-assisted analysis of antiwork/gumroad@afeacbd394 (2026-08-21). Data as JSON: /api/errors/c2b3c31cebf6a452. Report an issue: GitHub.

Appendix: source

Thrown at app/services/purchase/create_service.rb:331

        purchase = result[:purchase] || restartable_subscription.original_purchase
        self.purchase = purchase
        Rails.logger.info("Subscription #{restartable_subscription.external_id} restarted during checkout for product #{product.id}")
        return purchase, nil
      else
        return nil, result[:error_message]
      end
    end

    def create_gift
      # A seller buying their own product can only ever be a test purchase, and test purchases were
      # never built for gifts, so this case has to be rejected. The message names what the seller
      # actually did and points at the supported way to give a product away, because the old wording
      # ("Test gift purchases have not been enabled yet.") described an internal capability and read
      # as a flag we could switch on for them, which generated support tickets asking us to do that.
      raise Purchase::PurchaseInvalid, "You can't gift your own product. To give it away for free, create a 100% off discount code under Checkout > Discounts and share the checkout link." if buyer == product.user
      raise Purchase::PurchaseInvalid, "You cannot gift a product to yourself. Please try gifting to another email." if giftee_email == purchase_params[:email]
      raise Purchase::PurchaseInvalid, "Gift purchases cannot be on installment plans." if params[:pay_in_installments]

      if product.can_gift?
        gift = product.gifts.build(giftee_email:, gift_note: gift_params[:gift_note], gifter_email: params[:purchase][:email], is_recipient_hidden: gift_params[:giftee_email].blank?)
        error_message = gift.save ? nil : gift.errors.full_messages[0]
        raise Purchase::PurchaseInvalid, error_message if error_message.present?

        gift
      else
        error_message = product.user.gifting_disabled? ? "The creator has disabled gifting for their products." : "Gifting is not yet enabled for pre-orders."
        raise Purchase::PurchaseInvalid, error_message
      end
    end

    def validate_perceived_price
      if purchase_params[:perceived_price_cents] && !Purchase::MAX_PRICE_RANGE.cover?(purchase_params[:perceived_price_cents])
        raise Purchase::PurchaseInvalid, "Purchase price is invalid. Please check the price."
      end
    end

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