Ethereum Hardhat Error: TypeError Cannot Read Properties of Undefined
As a web3 developer, it’s not uncommon to encounter errors when working with the Ethereum blockchain using tools like Hardhat. In this article, we’ll tackle a common issue related to hardhat deployment on Node.js, which is often encountered by new users.
The Error Message: TypeError: Cannot Read Properties of Undefined (reading ‘0’)
When you run yarn hardhat deploy, your project should successfully compile and deploy your smart contracts. However, if you encounter the following error message:
TypeError: Cannot read properties of undefined (reading '0')
this indicates that there’s an issue with how Hardhat is handling your deployment process.
Why this Error Occurs
The TypeError: Cannot Read Properties of Undefined error occurs when Hardhat tries to access the 0th index of an array or object, but it doesn’t exist. In your case, this might be related to the way you’re using hardhat’s deploy function.
Solution 1: Check Your Deploy Code
One possible cause of this error is that your deploy code is not correctly setting up your deployment environment. Here are a few things to check:
- Make sure your
hardhat.config.jsfile is properly configured, including thenetworksanddeployersettings.
- Ensure that your
deployfunction is being called with the correct arguments.
Here’s an example of what your deploy 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 that you’re trying to access an undefined object. In your case, it might be related to using the ethers library.
To fix this issue, make sure you’ve installed and imported the ethers.js library correctly:
const ethers = require('ethers');
// ... other code ...
You can also try initializing ethers globally in your project’s package.json file:
"dependencies": {
"@nomiclabs/ethers": "^5.2.0",
// ... other dependencies ...
}
Solution 3: Check Your Hardhat Configuration
Hardhat has a configuration system that allows you to customize the deployment process. Here are a few things to check:
- Make sure your
hardhat.config.jsfile is properly configured, including any custom settings or overrides.
- Ensure that your
ethersProvideris correctly set up.
To fix this issue, make sure you’ve initialized ethers correctly in your project’s main file:
import * as ethers from 'ethers';
const provider = new ethers.providers.Web3Provider(window.ethereum);
const networkId = window.ethereum?.chainId;
// ... other code ...
By checking these possible solutions and testing them out, you should be able to resolve the TypeError: Cannot Read Properties of Undefined error when deploying your smart contracts with hardhat.
