🐶
Solidity

UnhandledPromiseRejectionWarning: Contract Code Not Stored

By Ondřej Dolanský on 11/27/2024

This article provides a solution to the "UnhandledPromiseRejectionWarning: Error: The contract code couldn't be stored, please check your gas limit" error.

UnhandledPromiseRejectionWarning: Contract Code Not Stored

Table of Contents

Introduction

Encountering the error "The contract code couldn't be stored, please check your gas limit" while deploying a smart contract to the Ethereum blockchain usually signifies an insufficient gas limit. To resolve this, it's crucial to understand how gas works in Ethereum and how to set appropriate limits.

Step-by-Step Guide

The error "The contract code couldn't be stored, please check your gas limit" usually pops up when you're trying to deploy a smart contract to the Ethereum blockchain, and the gas limit you've set is insufficient. Here's a breakdown of how to address this:

  1. Understanding Gas: Gas is the fee you pay for executing transactions on the Ethereum network. Deploying a contract is a transaction.
  2. Gas Limit: This is the maximum amount of gas you're willing to spend on the deployment. If the deployment requires more gas than your limit, it fails.
  3. Estimating Gas: Before deploying, estimate the gas needed: 
    const estimatedGas = await contract.deploy({
  // ... your deployment arguments
}).estimateGas();
  4. Setting Gas Limit: When deploying, set the gasLimit slightly higher than the estimated amount: 
    const deploymentTx = await contract.deploy({
  // ... your deployment arguments
}).send({
  from: yourAddress,
  gasLimit: estimatedGas * 1.2 // Add a buffer
});
  5. Manual Gas Limit: If estimation fails (e.g., due to complex logic), you might need to manually set a high enough gasLimit.
  6. Gas Price: While gasLimit is the maximum gas, gasPrice is what you pay per unit of gas. A higher gasPrice can speed up your transaction. 
    const deploymentTx = await contract.deploy({
  // ... your deployment arguments
}).send({
  from: yourAddress,
  gasLimit: estimatedGas * 1.2,
  gasPrice: ethers.utils.parseUnits('30', 'gwei') // Example gas price
});

Important Notes:

  • The error can also occur if there's a bug in your contract code that consumes excessive gas.
  • Always test deployments on a test network (like Rinkeby or Goerli) before deploying to the mainnet.
  • Monitor gas prices and adjust your gasPrice accordingly to avoid unnecessary costs.

Code Example

This JavaScript code demonstrates how to deploy an Ethereum smart contract using the ethers.js library. It connects to an Ethereum provider, estimates the gas needed for deployment, and deploys the contract with a gas limit buffer. The code also includes error handling for insufficient gas and other potential issues.

const { ethers } = require("ethers");
// ... import your contract artifact (ABI)

// Connect to your Ethereum provider (e.g., MetaMask, Infura)
const provider = new ethers.providers.Web3Provider(window.ethereum);
const signer = provider.getSigner();

// Create a contract instance
const MyContract = new ethers.ContractFactory(
  contractABI, // Your contract ABI
  contractBytecode, // Your contract bytecode
  signer
);

async function deployContract() {
  try {
    // Estimate gas needed
    const estimatedGas = await MyContract.deploy(
      /* ... your deployment arguments */
    ).estimateGas();

    console.log("Estimated gas:", estimatedGas.toString());

    // Deploy the contract with a gas limit buffer
    const deploymentTx = await MyContract.deploy(
      /* ... your deployment arguments */
    ).send({
      from: await signer.getAddress(),
      gasLimit: estimatedGas.mul(12).div(10), // Add a 20% buffer
      gasPrice: ethers.utils.parseUnits('30', 'gwei') // Optional: Set gas price
    });

    // Wait for the transaction to be mined
    await deploymentTx.wait();

    console.log("Contract deployed to:", deploymentTx.contractAddress);
  } catch (error) {
    console.error("Contract deployment failed:", error);
    // Handle errors, including insufficient gas errors
    if (error.code === -32000 && error.message.includes("gas")) {
      console.log("Insufficient gas. Consider increasing the gas limit.");
    }
  }
}

deployContract();

Explanation:

  1. Import necessary libraries: Import ethers.js for interacting with the Ethereum blockchain.
  2. Connect to provider: Establish a connection to your Ethereum provider.
  3. Contract instance: Create a contract instance using your contract's ABI and bytecode.
  4. Estimate gas: Use estimateGas() to get an estimate of the gas required for deployment.
  5. Deploy with gas limit: Deploy the contract using the deploy() method, setting the gasLimit to the estimated gas plus a buffer (e.g., 20%).
  6. Optional: Set gas price: You can optionally set the gasPrice to influence transaction speed.
  7. Handle errors: Use a try...catch block to handle potential errors during deployment, including insufficient gas errors.

Remember:

  • Replace placeholders like contractABI, contractBytecode, and deployment arguments with your actual values.
  • Adjust the gasLimit buffer and gasPrice based on network conditions and your requirements.
  • Thoroughly test your contract on a test network before deploying to the mainnet.

Additional Notes

  • Deployment Complexity: More complex contracts with larger bytecode or intricate deployment logic will generally require higher gas limits.
  • Contract Optimization: Writing efficient contract code can significantly reduce gas consumption. Consider using gas optimization techniques during development.
  • Gas Estimation Errors: While estimateGas is usually accurate, it can sometimes underestimate in certain scenarios. Always add a buffer to the estimated gas limit to account for this.
  • Transaction Fees: The total transaction fee for deployment is calculated as gasUsed * gasPrice. Even if you set a high gasLimit, you only pay for the gas actually used. Unused gas is refunded.
  • Block Gas Limit: Each Ethereum block has a maximum gas limit. If your deployment transaction requires more gas than the current block limit, it will fail. You might need to wait for a block with a higher limit or reduce your contract's gas consumption.
  • Development Environments: Consider using tools like Hardhat or Truffle, which provide development environments with built-in features for deploying and testing contracts, including gas management.
  • Ethereum Clients: Different Ethereum clients (e.g., Geth, Parity) might have slightly different gas estimation and handling mechanisms. Be aware of potential variations.
  • Gas Trackers: Utilize gas trackers like https://etherscan.io/gastracker to monitor current gas prices and network congestion. This can help you optimize your gasPrice for faster or cheaper transactions.
  • Error Analysis: If you encounter the "contract code couldn't be stored" error, carefully examine the transaction details and error messages for clues. This can help pinpoint whether the issue is related to gas, contract code, or other factors.

Summary

This error occurs when deploying a smart contract with insufficient gas limit, which is the maximum fee you're willing to pay for the deployment transaction.

Here's how to fix it:

  1. Estimate Gas: Use contract.deploy(...).estimateGas() to get an estimate of the gas required.
  2. Set Gas Limit: When deploying, set gasLimit slightly higher (e.g., 1.2x) than the estimated value.
  3. Manual Adjustment: If estimation fails, manually set a high enough gasLimit.
  4. Consider Gas Price: gasPrice determines the cost per unit of gas. Higher prices can speed up transactions.

Additional Tips:

  • Debugging: The error can also indicate a gas-consuming bug in your contract.
  • Test Networks: Always test deployments on test networks before the mainnet.
  • Monitor Gas Prices: Adjust your gasPrice based on network conditions to optimize costs.

Conclusion

In conclusion, encountering the "The contract code couldn't be stored, please check your gas limit" error during smart contract deployment on Ethereum typically points to an insufficient gas limit. By understanding the role of gas in Ethereum and following the outlined steps to estimate and set appropriate gas limits, developers can overcome this hurdle. Remember to incorporate a buffer for gas estimation variations and consider network gas prices for cost optimization. Utilizing test networks and employing robust error handling further streamlines the deployment process. By adhering to these practices, developers can ensure their smart contracts are deployed successfully and efficiently on the Ethereum blockchain.

References

Were You Able to Follow the Instructions?

😍Love it!
😊Yes
😐Meh-gical
😞No
🤮Clickbait

Related posts

Ethereum DApp User Profile Management

Learn how to securely manage user profiles and data in your Ethereum decentralized applications (DApps) using best practices and smart contracts.

Solidity "Pure" Function Warning: Optimization Guide

Learn how to optimize your Solidity code and improve gas efficiency by understanding when to restrict function state mutability to "pure" for functions that don't modify or read blockchain state.

Solidity Default Function Parameters: A How-To Guide

Learn how to define default parameter values in Solidity functions for enhanced flexibility and code readability in your smart contracts.