Ethereum: Error -26: required-script-verify-flag-failed (signature must be null if CHECK(MULTI)SIG operation failed)

Ethereum Error 26: Mandatory Script Verify Flag Failed

As a developer or user of Ethereum, you may encounter the following error when trying to send transactions using the sendrawtransaction method:

{"error":{"code":-26,"message":"mandatory-script-verify-flag-failed (Signature must be zero for failed CHECK(MULTI)SIG operation)"}}

This error occurs because the Ethereum network is attempting to verify the signature of a transaction before it can be confirmed. However, there was an issue with the script that generated the transaction.

Understanding the Error

In Ethereum, transactions are signed using the ECDSA (Elliptic Curve Digital Signature Algorithm) algorithm. The sendrawtransaction method generates a raw transaction in the form of an ABI (Application Binary Interface) encoded message.

The error occurs when the network attempts to verify the signature of this message using the mandatory-script-verify-flag-failed flag. This flag is used to prevent malicious transactions from being confirmed without proper verification.

Causes of the Error

There are several possible causes of this error:

• Invalid transaction data: The transaction data may be invalid or incomplete, causing the network to fail in verifying the signature.

• Incorrect script flags: The mandatory-script-verify-flag-failed flag is set incorrectly, which prevents the network from verifying the signature properly.

• Missing script signature: The transaction does not contain a valid ECDSA private key signature, which is required for verification.

Troubleshooting Steps

To resolve this error, follow these steps:

• Check transaction data

  

  : Verify that the transaction data is correct and complete.

• Verify script flags: Double-check that the mandatory-script-verify-flag-failed flag is set correctly to 0.

• Add a private key signature: Add a valid ECDSA private key signature to your transaction data, using a tool like ethers.js or web3.js.

• Use a trusted wallet: Ensure that you are using a trusted wallet or tool to sign and verify transactions.

Example

Here is an example of how to add a private key signature to a transaction:

const transaction = {

  // ...

  inputs: [

    // ...

  ],

  outputs: [

    // ...

  ],

  gasLimit: '100000',

  nonce: '0x1234567890abcdef',

  data: '0x0123456789abcdef',

  privateKey: '0x0123456789abcdef', // Add a valid ECDSA private key signature

};


const transactionBytes = ethers.utils.solidity.printTransaction(transaction);

Conclusion

The mandatory-script-verify-flag-failed error occurs when the Ethereum network is unable to verify the signature of a transaction without proper script flags. By checking the transaction data, verifying script flags, adding a private key signature, and using a trusted wallet or tool, you should be able to resolve this issue and send transactions successfully.

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