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

# AA25: Nonce Mismatch

> Addressing invalid nonce issues in user operations

The `nonce` provided in your user operation is invalid.

## Resolution Strategies

1. Nonce Verification:
   * Ensure you're using the correct current nonce for the smart account and selected `key`
   * Consider using [`getAccountNonce`](/permissionless/reference/public-actions/getAccountNonce)

2. Common Pitfalls:
   * Avoid reusing previously used nonces
   * Don't use nonces too far in the future (no more than 10 ahead of current nonce)

3. Formatting Check:
   * Verify correct nonce format

4. Parallel Transaction Handling:
   * For concurrent operations, utilize custom nonce `key`
   * Refer to [Parallel Transaction Guide](/permissionless/how-to/parallel-transactions##sending-multiple-transactions-in-parallel)

<Note>
  Nonce Structure:
  The EntryPoint uses a 256-bit nonce, split into:

  * 192-bit `key`
  * 64-bit `sequence`
    Each `key` has its own sequential `sequence`, allowing new `key` introduction with arbitrary values.
</Note>