> ## Documentation Index > Fetch the complete documentation index at: https://yn-c9bb3266.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Update Checkout Session > Updates an existing checkout session. You can modify the amount, metadata, or other mutable fields before the session expires or a payment is completed. ## OpenAPI ````yaml PATCH /v1/checkout/sessions/{checkout_session_id} openapi: 3.1.0 info: title: Yuno Payments API description: >- Yuno payment orchestration platform — unified REST API for payments, checkout sessions, customers, payment methods, subscriptions, payouts, marketplace transfers, and banking connectivity across Latin America. version: 1.0.0 contact: name: Yuno Support email: support@y.uno url: https://docs.y.uno license: name: Proprietary url: https://y.uno servers: - url: https://api-sandbox.y.uno description: Sandbox - url: https://api.y.uno description: Production security: - publicApiKey: [] privateSecretKey: [] paths: /v1/checkout/sessions/{checkout_session_id}: patch: tags: - Checkout Sessions summary: Update checkout session description: >- Updates an existing checkout session. You can modify the amount, metadata, or other mutable fields before the session expires or a payment is completed. operationId: updateCheckoutSession parameters: - name: checkout_session_id in: path required: true description: The unique identifier of the checkout session to update schema: type: string format: uuid example: a1b2c3d4-e5f6-7890-abcd-ef1234567890 requestBody: required: true content: application/json: schema: type: object properties: amount: type: object description: Updated payment amount properties: currency: type: string description: ISO 4217 currency code example: BRL value: type: number description: Payment amount example: 200 metadata: type: object description: Key-value pairs for storing additional information additionalProperties: type: string example: order_id: ORD-789 updated_reason: price_adjustment merchant_order_id: type: string description: Updated merchant order reference example: order-updated-456 example: amount: currency: BRL value: 200 metadata: order_id: ORD-789 responses: '200': description: Checkout session updated successfully content: application/json: schema: $ref: '#/components/schemas/CheckoutSession' '400': description: Invalid request body content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Checkout session not found content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: Checkout session cannot be updated (already completed or expired) content: application/json: schema: $ref: '#/components/schemas/Error' x-codeSamples: - lang: bash label: cURL source: |- curl --request PATCH \ --url https://api-sandbox.y.uno/v1/checkout/sessions/a1b2c3d4-e5f6-7890-abcd-ef1234567890 \ --header 'Content-Type: application/json' \ --header 'public-api-key: YOUR_PUBLIC_API_KEY' \ --header 'private-secret-key: YOUR_PRIVATE_SECRET_KEY' \ --data '{ "country": "BR", "amount": { "currency": "ARS" }, "merchant_order_id": "order-updated-456", "payment_description": "Updated payment description", "account_id": "YOUR_ACCOUNT_CODE", "metadata": { "order_id": "ORD-789" } }' components: schemas: CheckoutSession: type: object properties: checkout_session: type: string format: uuid description: The checkout session identifier example: a1b2c3d4-e5f6-7890-abcd-ef1234567890 amount: $ref: '#/components/schemas/Amount' country: type: string description: ISO 3166-1 alpha-2 country code example: BR merchant_order_id: type: string description: Your unique order identifier example: order-20260301-001 status: type: string description: Session status example: ACTIVE created_at: type: string format: date-time description: Session creation timestamp example: '2026-03-01T14:30:00.000Z' payment_methods: type: array items: type: object properties: type: type: string description: Payment method type description: Available payment methods for this session callback_url: type: string format: uri description: URL to receive server-side payment notifications example: https://merchant.com/webhooks/yuno return_url: type: string format: uri description: >- URL to redirect the customer after payment completion (required for 3DS, PIX, and redirect-based methods) example: https://merchant.com/checkout/complete example: checkout_session: a1b2c3d4-e5f6-7890-abcd-ef1234567890 amount: currency: BRL value: 150 country: BR merchant_order_id: order-20260301-001 status: ACTIVE created_at: '2026-03-01T14:30:00.000Z' payment_methods: - type: CARD - type: PIX - type: BOLETO Error: type: object description: >- Standard error envelope returned by every Yuno service for any 4xx or 5xx response. Top level. `code` is a stable SCREAMING_SNAKE_CASE identifier. `messages` is always an array of strings, even when there is only one entry. There is no `error` wrapper, no singular `message`, no `type`, no `details`. See the Error handling guide for the full code catalog. required: - code - messages properties: code: type: string description: >- Stable, machine readable identifier. Branch on this in your client. Common values include `BAD_REQUEST`, `VALIDATION_ERROR`, `INVALID_REQUEST`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `TOO_MANY_REQUESTS`, `INTERNAL_ERROR`, `BAD_GATEWAY`, `SERVICE_UNAVAILABLE`, plus business codes like `CUSTOMER_ID_DUPLICATED`, `RECIPIENT_NOT_FOUND`, `INVALID_STATE`, and the `PROVIDER_*` family for downstream provider errors. example: VALIDATION_ERROR messages: type: array description: >- Human readable details. Validation errors put one entry per failed field, formatted `"fieldName message"`. items: type: string example: - merchant_customer_id must not be blank example: code: VALIDATION_ERROR messages: - amount must be greater than 0 - country must not be blank Amount: type: object required: - currency - value properties: currency: type: string description: ISO 4217 currency code example: BRL value: type: number description: >- Payment amount in major currency units (e.g., 150.00 means 150 BRL, not cents). For zero-decimal currencies like CLP and PYG, use whole numbers (e.g., 15000 means 15,000 CLP). example: 100 example: currency: BRL value: 100 securitySchemes: publicApiKey: type: apiKey in: header name: public-api-key description: Your public API key from the Yuno Dashboard privateSecretKey: type: apiKey in: header name: private-secret-key description: Your private secret key (server-side only) ````