Checkout Result Codes

When handling the webhook response from MMG, the decrypted payload will contain a ResultCode and a ResultMessage. You must evaluate the ResultCode to determine whether to fulfill the customer’s order or mark it as failed.

Only fulfill orders when you receive a ResultCode of "0". Any other code indicates that the transaction did not complete successfully.

Status Codes Table

Use the following table to map the outcome of the checkout session:

Result Code	Message	Description	Action to Take
`0`	Transaction Successful	Payment was successful; Merchant can release product/service/goods.	Fulfill Order.
`1`	Agent Not Registered	User is not registered with MMG.	Mark as failed. Prompt user to register or use another method.
`2`	Payment Failed	Payment has failed.	Mark as failed. Prompt user to try again.
`3`	Invalid Secret Key	Secret Key is invalid (possible phishing or configuration issue).	Check your environment variables and SDK configuration.
`4`	Merchant ID Mismatch	Merchant ID did not match Merchant ID in the encrypted token.	Verify the `merchantId` passed during token generation.
`5`	Token Decryption Failed	Incoming token is invalid or cannot be decrypted.	Check your PEM keys and ensure formatting is correct.
`6`	Transaction Cancelled	User clicked Cancel during Checkout.	Mark order as cancelled. Return user to cart.
`7`	Request Timed Out	The request timed out.	Mark order as abandoned/failed.

Handling Edge Cases

Missing Webhooks: If a user closes their browser before MMG can send the webhook, or if your server experiences downtime, you may miss the callback. It is highly recommended to implement a cron job or scheduled task that uses the Transaction Lookup API to check the status of any pending orders after a certain time period (e.g., 15 minutes).
Duplicate Webhooks: Ensure your webhook handler is idempotent. If MMG sends the same transactionId twice, your system should recognize that the order is already paid and gracefully ignore the duplicate request while still returning a 200 OK.