> ## Documentation Index
> Fetch the complete documentation index at: https://developers.circle.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshoot CCTP transfers

> Diagnose and resolve stuck or failed crosschain USDC transfers

This guide helps you diagnose and resolve issues with CCTP transfers that appear
stuck or fail to complete. A CCTP transfer involves three stages, and problems
can occur at any point in the process.

## Transfer stages

A CCTP transfer consists of three stages:

1. **Burn**: USDC is burned on the source blockchain
2. **Attestation**: Circle's Attestation Service observes the burn and signs a
   message
3. **Mint**: The signed attestation is submitted to mint USDC on the destination
   blockchain

If your transfer appears stuck, first identify which stage has the issue.

## Identify where your transfer is stuck

Use the following steps to determine the current state of your transfer:

<Steps>
  <Step title="Check the burn transaction">
    Verify the burn transaction succeeded on the source blockchain using a block
    explorer. If the transaction failed or is pending, the issue is at the burn
    stage.
  </Step>

  <Step title="Query the attestation API">
    Call the [`GET /v2/messages`](/api-reference/cctp/all/get-messages-v2) endpoint
    with your transaction hash.

    Interpret the response:

    * **404 response**: The attestation service hasn't observed the burn yet. This
      is normal and expected. See
      [Why 404 responses are expected](/cctp/howtos/resolve-stuck-attestation#why-404-responses-are-expected).
    * **Empty `messages` array**: The burn exists but hasn't been processed yet.
    * **Status `pending`**: The burn is awaiting block confirmations.
    * **Status `complete` with attestation**: The attestation is ready. If your
      transfer is stuck, the issue is at the mint stage.
  </Step>

  <Step title="Check the mint transaction">
    If you have an attestation but your destination wallet doesn't have the USDC,
    either:

    * The mint transaction was never submitted
    * The mint transaction failed

    Check your destination blockchain for any failed `receiveMessage` transactions.
  </Step>
</Steps>

## Common issues and solutions

| Issue                                                      | Cause                                                                                                                                                                          | Solution                                                                                                                                                                                                                           |
| ---------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 404 persists for extended time                             | Burn transaction may have failed or is still confirming                                                                                                                        | Verify burn succeeded on block explorer. If it failed, retry the burn.                                                                                                                                                             |
| Attestation status remains `pending`                       | Waiting for block confirmations                                                                                                                                                | Wait for sufficient confirmations based on finality threshold                                                                                                                                                                      |
| Have attestation but mint fails                            | Gas issues, incorrect parameters, or nonce already used                                                                                                                        | See [Retry a failed mint](/cctp/howtos/retry-failed-mint)                                                                                                                                                                          |
| `expirationBlock` has passed before you submitted the mint | Attestations encode an `expirationBlock` 24 hours in the future. Once that block passes on the destination blockchain, the existing attestation can no longer be used to mint. | Call [`POST /v2/reattest/{nonce}`](/api-reference/cctp/all/reattest-message) to request a new attestation with a refreshed `expirationBlock`, then poll [`GET /v2/messages`](/api-reference/cctp/all/get-messages-v2) and re-mint. |

<Note>
  **Expired messages are not permanently stuck**

  There is no deadline after which re-attestation becomes unavailable. As long as
  the original burn transaction still exists on the source blockchain, you can
  request a fresh attestation at any time using the
  [re-attest endpoint](/api-reference/cctp/all/reattest-message).
</Note>