Error deploying Mern Stack application on Heroku - node.js

Question

I am trying to deploy a full-stack app on heroku, i have tried couple of things but none of them worked... when i entered "heroku logs" to follow up with the errors it should me code: 'MODULE_NOT_FOUND even though the node_module's can be found in both the Root of the project and the Frontend file as well , how do i fix this error and where does it come from ?
Here's a picture of my projects structure:
server.js:
require('dotenv').config();
const path = require('path');
const express = require("express");
const productRoutes = require("./routes/productRoutes");
const connectDB = require("./config/db");
connectDB();
const app = express();
app.use(express.json());
//--------------- deployment -------
app.use("/api/products", productRoutes);
if(process.env.NODE_ENV === "production") {
app.use(express.static(path.join('../frontend/build')));
app.get('*',(req,res) => {
res.sendFile(path.resolve(__dirname,'../frontend/build','index.html'))
})
} else {
app.get("/", (req, res) => {
res.send("Api running");
})
}
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));
.env:
PORT=8080
MONGO_URI=*****
NODE_ENV=production
Package.json:
{
"name": "mern-shopping-build",
"version": "1.0.0",
"description": "Shopping list built with MERN stack",
"main": "server.js",
"engines": {
"node": "16.4.1",
"npm": "7.18.1"
},
"scripts": {
"build": "cd frontend && npm run dev",
"install-client": "cd frontend && npm install",
"heroku-postbuild": "npm run install-client && npm run build",
"start": "node server.js",
"server": "nodemon backend/server.js",
"client": "npm start && cd frontend",
"dev": "concurrently --kill-others-on-fail \"npm run server\" \"npm start --prefix frontend\""
},
"keywords": [],
"author": "Karim ",
"license": "ISC",
"dependencies": {
"cors": "^2.8.5",
"dotenv": "^10.0.0",
"express": "^4.17.1",
"mongoose": "^5.13.2"
},
"devDependencies": {
"concurrently": "^6.2.0",
"nodemon": "^2.0.9"
}
}
ProcFile:
web node server.js
I Would appreciate any kind of feedback or help, Thank you!

Answer 1

A Procfile is not technically required to deploy simple apps written in most Heroku-supported languages—the platform automatically detects the language and creates a default web process type to boot the application server.
Just make sure to point your root package.json main key to backend/server.js.
Most likely it would work otherwise share your Build Logs to check it further.
{
"main": "backend/server.js"
}