Ethereum: TypeError: Cannot read properties of undefined (reading ‘0’) while running `yarn hardhat deploy`
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 0
th index of an array or object, but it does not 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 out:
- Make sure your
hardhat.config.js
file is configured properly, including thenetworks
anddeployer
settings.
- Ensure that your
deploy
function is being called with the correct arguments.
Here is an example of what your deploy code might look like:
module.exports = {
// ... other configurations
networks: {
mainnet: {
accounts: [
'0x1234567890123456789012345678901234567890',
'0x9876543210987654321098765432109876543210'
],
gas: 200,000,
gasPrice:
} }
},
deploy: {
network: mainnet,
// ... more 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 ' ) ;
// ... more 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 out:
- Make sure your
hardhat.config.js
file is configured properly, including any custom settings or overrides.
- Ensure that your
ethersProvider
is set up correctly.
To fix this issue, make sure you’ve initialized ethers correctly in your project’s main file:
import * and ethers from 'ethers';
const provider = new ethers . providers . Web3Provider ( window . ethereum ) ;
const networkId = window.ethereum?.chainId;
// ... more 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.