[General] Failed paymaster validation

[pacelliv]

Team or Project

No response

Environment

Testnet

L2 block number

No response

Provide a brief description of the functionality you're trying to implement and the issue you are running into.

I'm following the Paymaster introduction from the docs, currently, I'm stuck trying to calculate the fee estimation, I managed to debug the error is happening when I call the estimateGas method of the contract object.

The error is:

  shortMessage: 'failed paymaster validation. error message: Error function_selector = 0xe450d38c, data = 0xe450d38c000000000000000000000000cc8188e984b4c392091043caa73d227ef5e0d0a700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001'

This a smar snippet of code:

  const paymasterParamsForFeeEstimation = utils.getPaymasterParams(
    testnetPaymasterAddress!,
    {
      type: "ApprovalBased",
      token: TOKEN_CONTRACT_ADDRESS,
      // Set to 1 wei ony for gas estimation
      minimalAllowance: ethers.toBigInt(1),
      // Empty bytes as tesnet paymaster does not use innerInput
      innerInput: new Uint8Array(0),
    }
  );

  // Error on the next line
  const gasLimit = await zeekMessages.sendMessage.estimateGas(NEW_MESSAGE, {
    customData: {
      gasPerPubdata: utils.DEFAULT_GAS_PER_PUBDATA_LIMIT,
      paymasterParams: paymasterParamsForFeeEstimation,
    },
  });

I've compared my code with the one on the tutorial, but I've not managed to figure out the reason of the error.

Repo Link (Optional)

https://github.com/pacelliv/example

Additional Details

I also tried running the script on Atlas with the provided code, but it also reverts.

[alhenaai[bot]]

It seems like you are encountering an issue with the estimateGas method during the paymaster validation process. The error message indicates a problem with the function selector and data being passed to the paymaster.

Here are a few steps you can take to troubleshoot and potentially resolve this issue:

1. Verify Paymaster Address and Token Contract Address: Ensure that the testnetPaymasterAddress and TOKEN_CONTRACT_ADDRESS are correctly set and point to the correct contracts on the testnet.

2. Check the Paymaster Contract: Review the paymaster contract to ensure it supports the ApprovalBased type and that it is set up to handle the function selector 0xe450d38c. This might involve checking the contract's code on a block explorer or in your development environment.

3. Minimal Allowance and Inner Input: Double-check that setting the minimalAllowance to 1 wei and using an empty innerInput are appropriate for your paymaster's requirements. Some paymasters might have specific needs regarding these parameters.

4. Review Custom Data: Make sure that gasPerPubdata and other custom data fields are correctly configured according to the paymaster's expectations.

5. Contract Method Compatibility: Ensure that the zeekMessages.sendMessage.estimateGas method is compatible with the paymaster parameters you are passing. There might be a mismatch in expected parameters or configuration.

6. Testing and Debugging: Consider adding more logging around the estimateGas call to capture and log the full request and response. This might provide more insight into what is going wrong.

7. Consult Documentation and Community: Review the Paymasters introduction again for any updates or additional tips. Also, consider reaching out on the ZKsync developers discussions for more targeted help from the community.

If these steps do not resolve the issue, it might be helpful to provide a more detailed error log or seek direct support from the ZKsync developer community.

Your feedback helps us serve you better. If this fully addresses your question, please give it a thumbs up. If it doesn't, please give it a thumbs down. This will inform the community and team so we can improve our support.

[uF4No]

Most likely the problem is that the account that you're using does not have any balance of the ERC20 token you're using. To give you more context on what we're doing in this transaction, the paymaster will receive 1 unit of the ERC20 token from your wallet, and then the paymaster will pay the original transaction fee in ETH.

I've amended your script to print the balance of the token so you can verify if that's the issue (see below).

In addition, you can use the test token 0x2192F14Eeb0D8c9Bf92D81D30696bEB562Fa9490, which I have deployed and verified in our testnet. It's a minteable token, so you can mint some to your account and use it in your script (you can do it from here).

import hre, { ethers } from "hardhat";
import { Provider, Contract, utils, Wallet } from "zksync-ethers";
import zeekMessagesAbi from "../abis/zeekMessages.json";
import tokenAbi from "../abis/token.json";
import "@matterlabs/hardhat-zksync-node/dist/type-extensions";

// Address of the my deployed ZeekMessages contract
const ZEEK_MESSAGES_CONTRACT_ADDRESS =
  "0x622595bcd513c8A531632dBAFA3F7A92629CBce7";
// Address of my deployed MockToken contract
const TOKEN_CONTRACT_ADDRESS = "0x6baaD061bf14f53cE608ae00C0Ff2DE907aB6812";
// Message to send
const NEW_MESSAGE = "Hello ZkSync from Pacelli! :)";
// Private key from .env file
const WALLET_PRIVATE_KEY = process.env.WALLET_PRIVATE_KEY;

if (!WALLET_PRIVATE_KEY) {
  throw new Error("⛔️ Cannot find private key.");
}

if (!ZEEK_MESSAGES_CONTRACT_ADDRESS) {
  throw new Error("⛔️ Cannot find the address of the ZeekMessages contract.");
}

if (!TOKEN_CONTRACT_ADDRESS) {
  throw new Error("⛔️ Cannot find the address of the token contract.");
}

if (!NEW_MESSAGE) {
  throw new Error(
    "⛔️ Cannot find message to send to the ZeekMessages contract."
  );
}

const main = async () => {
  // Create provider instance
  const zkProvider = new Provider(hre.network.config.url);
  // Create wallet instance
  const wallet = new Wallet(WALLET_PRIVATE_KEY, zkProvider);
  // Create instance of ZeekMessages contract
  const zeekMessages = new Contract(
    ZEEK_MESSAGES_CONTRACT_ADDRESS,
    zeekMessagesAbi,
    wallet
  );
  // Create instance of MockToken contract
  const token = new Contract(TOKEN_CONTRACT_ADDRESS, tokenAbi, wallet);

  // Get token balance
  const balance = await token.balanceOf(wallet.address);
  console.log(`Balance of ${wallet.address} is ${ethers.formatEther(balance)} tokens`);
  // Get testnet paymaster address
  const testnetPaymasterAddress = await zkProvider.getTestnetPaymasterAddress();
  console.log(`Testnet paymaster address is ${testnetPaymasterAddress}`);
  // Get network gas price
  const gasPrice = await zkProvider.getGasPrice();
  // Define paymaster parameters for gass estimation
  const paymasterParamsForFeeEstimation = utils.getPaymasterParams(
    testnetPaymasterAddress!,
    {
      type: "ApprovalBased",
      token: TOKEN_CONTRACT_ADDRESS,
      // Set to 1 wei ony for gas estimation
      minimalAllowance: ethers.toBigInt(1),
      // Empty bytes as tesnet paymaster does not use innerInput
      innerInput: new Uint8Array(0),
    }
  );

  /////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // __________________________________________
  // ( I don't understand why this is happening )
  //  ------------------------------------------
  //         o   ^__^
  //          o  (xx)\_______
  //             (__)\       )\/\
  //              U  ||----w |
  //                 ||     ||

  // Error on the next line
  const gasLimit = await zeekMessages.sendMessage.estimateGas(NEW_MESSAGE, {
    customData: {
      gasPerPubdata: utils.DEFAULT_GAS_PER_PUBDATA_LIMIT,
      paymasterParams: paymasterParamsForFeeEstimation,
    },
  });

  // Fee calculated in ETH will be same amount of ERC20 used in the paymaster
  const fee = gasPrice * gasLimit;
  console.log(`Fee: ${ethers.formatEther(fee)} ETH`);
};

main().catch((error) => {
  console.error(error);
  process.exit(1);
});

[pacelliv]

You were correct, I needed to mint tokens in order to calculate the gasLimit. I appreciate your help.