Lesson 5: Interacting with contracts in EthersJS | Error: Cannot find module 'ethers'

[CoinAdopter]

Hello! I am running into an error. I can't pinpoint what was done that caused this to happen but I can say this started as soon as I installed the dotenv library to manage environment variables. The error I get is shown below. My deploy.js code is below the error. Thank you in advance for your help!

juan@Juans-MacBook-Air New Program % node deploy.js
node:internal/modules/cjs/loader:936
throw err;
^

Error: Cannot find module 'ethers'
Require stack:

• /Users/juan/Desktop/New Program/deploy.js
  at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
  at Function.Module._load (node:internal/modules/cjs/loader:778:27)
  at Module.require (node:internal/modules/cjs/loader:1005:19)
  at require (node:internal/modules/cjs/helpers:102:18)
  at Object. (/Users/juan/Desktop/New Program/deploy.js:1:16)
  at Module._compile (node:internal/modules/cjs/loader:1101:14)
  at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
  at Module.load (node:internal/modules/cjs/loader:981:32)
  at Function.Module._load (node:internal/modules/cjs/loader:822:12)
  at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [ '/Users/juan/Desktop/New Program/deploy.js' ]
  }

and my deploy.js code looks like this:

const ethers = require("ethers");
const fs = require("fs");
require("dotenv").config();

async function main() {
  const provider = new ethers.providers.JsonRpcProvider(
    "http://127.0.0.1:7545"
  ); //connection to the blockchain, in this case ganache
  const wallet = new ethers.Wallet(process.env.PRIVATE_KEY, provider); //wallet with private key (dotenv) to sign transactions
  const abi = fs.readFileSync("./SimpleStorage_sol_SimpleStorage.abi", "utf-8");
  const binary = fs.readFileSync(
    "./SimpleStorage_sol_SimpleStorage.bin",
    "utf-8"
  );
  const contractFactory = new ethers.ContractFactory(abi, binary, wallet);
  console.log("Deploying, please wait.....");
  const contract = await contractFactory.deploy(); //we are telling the code, STOP here and wait for contract to deploy!
  await contract.deployTransaction.wait(1); // not sure about this at this point

  const currentFavoriteNumber = await contract.retrieve(); //since it's a view function, no gas

  console.log(`Current Favorite Number: ${currentFavoriteNumber.toString()}`); //to show number and not Hex
  const transactionResponse = await contract.store("9");
  const transactionReceipt = await transactionResponse.wait(1); //wait for 1 block
  const updatedFavoriteNumber = await contract.retrieve();
  console.log(`Updated Favorite Number: ${updatedFavoriteNumber.toString()}`); // shows updated number
}

main()
  .then(() => process.exit(0))
  .catch((error) => {
    console.error(error);
    process.exit(1);
  });

[alymurtazamemon]

@CoinAdopter remove the node_modules folder and run npm install and make sure you are on root level and package.json exist there.

[CoinAdopter]

I tried your suggestion but it did not work. However, I tried re-installing Ethers with NPM and that solved the problem. I had installed it with Yarn as Patrick showed us in the class and it worked for a while. Anyhow, once I used "npm install --save ethers" , the deploy.js file started to work just fine. Thanks for your help!

[alymurtazamemon]

@CoinAdopter In your case the missing node_module was dev_dependency that's why the command npm install did not work because it does not install dev-dependencies automatically for it you need to use npm install --dev and it will install the dev dependencies. I did not know that your missing module was dev-dependency.

Well, this will help others in the future.

Run both commands in case you see the MODULE NOT FOUND error, first remove the node_modules folder, then run

npm install will install all the missing dependencies.

and then run npm install --dev and it will install all missing dev-dependencies.

and then your issue will be resolved.