> ## 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.

# AA24: Signature Validation Failure

> Resolving signature rejection issues in validateUserOp

The smart account's `validateUserOp` function has rejected the user operation's signature.

## Resolution Checklist

1. Signature Accuracy:
   * Verify correct signing of the user operation
   * Ensure proper encoding in the `signature` field

2. UserOpHash Computation:
   * Confirm correct calculation of `userOpHash`
   * Consider using [`getUserOperationHash`](/permissionless/reference/utils/getUserOperationHash)

3. Chain and EntryPoint Verification:
   * Double-check `chainId` and `entryPointAddress` in `userOpHash` computation

4. Smart Account Implementation:
   * Review the signature verification logic in your smart account

5. Advanced Troubleshooting:
   * Employ [Tenderly](https://tenderly.co/) or similar tools to investigate `validateUserOp` behavior