Ethereum Hardhat Error: TypeError cannot read properties of undefined

As a web3 developer, I often encounter errors when working with the Ethereum blockchain using tools like Hardhat. In this article, we will cover a common issue with the Hardhat implementation in Node.js that new users often encounter.

Error Message: TypeError: Cannot read properties of undefined (reading ‘0’)

After running ‘yarn hardhat deploy’, your project should successfully compile and deploy your smart contracts. However, if you receive the following error message:

TypeError: Cannot read properties of undefined (reading '0')

this means that there is an issue with the way Hardhat handles the deployment process.

Why does this error occur?

The “TypeError: Cannot read properties of undefined element” error occurs when Hardhat tries to access index “0” of an array or object that does not exist. In your case, this may be related to how you are using Hardhat’s “deploy” function.

Solution 1: Check your deployment code

A possible cause of this error is that the deployment code is not properly configuring the deployment environment. Here are some things to check:

• Make sure your hardhat.config.js file is configured correctly, including the networks and deployer settings.

• Make sure the deploy function is called with the correct arguments.

Here’s an example of what your deployment code might look like:

module.exports = {
// ... other configurations ...
networks: {
mainnet: {
accounts: [
'0x1234567890123456789012345678901234567890',
'0x9876543210987654321098765432109876543210'
],
gas: 200000,
gasPrice: 20
}
},
deployer: {
network: 'mainnet',
// ... other settings ...
},
async deploy() {
await this.deployed();
return this state ;
}
};

Solution 2: Use the ‘ethers’ library

Another possible cause of this error is trying to access an undefined object. In your case, this may be related to using the ‘ethers’ library.

To fix this, make sure you have correctly installed and imported the ‘ethers.js’ library:

const ethers = require('ethers');
// ... some more code ...

You can also try initializing ethers globally in your project’s package.json file:

"dependencies": {
"@nomiclabs/ethers": "^5.2.0",
// ... more dependencies ...
}

Solution 3: Check the headset configuration

Hardhat has a configuration system that allows you to customize the deployment process. Here are some things to check:

• Make sure your hardhat.config.js file is configured correctly, including any custom settings or overrides.

• Make sure ethersProvider is configured correctly.

To fix this, make sure you have initialized ethers properly in your project’s main file:

import * as ethers from 'ethers';
const provider = new ethers.providers.Web3Provider(window.ethereum);
const networkId = window.ethereum?.chainId;
// ... some more code ...

By checking these possible solutions and testing them, you should be able to resolve the “TypeError: Cannot read properties of Undefined” error when deploying smart contracts using hardhat.