Error: Cannot find module 'express' |
Express is not installed or node_modules is missing |
Run npm install express to install Express. If the issue continue, try deleting node_modules and package-lock.json, then run npm install again. |
| 404 Not Found for a defined route |
The port you are trying to use is already in use |
Change the port number in app.listen(PORT), or stop the process using the port (npx kill-port 3000). |
| Static Files (CSS, JS, images) are not loading |
Static file directory is not set correctly. |
Ensure you have app.use(express.static("public")) and the static files are inside the public folder. |
| Middleware is not working as expected |
Middleware is not placed in the correct order. |
Ensure middleware is added before defining routes that depend on it |
req.body is undefined in POST requests |
express.json() middleware is missing. |
Add app.use(express.json()) and app.use(express.urlencoded({ extended: true})) before defining routes. |
Error: Cannot find module 'dotenv' |
dotenv package is not installed |
Run npm install dotenv to install the package. |
| Environment variables not working |
.env file is not loaded or variables are not defined correctly |
Ensure you have require('dotenv').config() at the top of your server.js file and check the .env file for correct variable definitions. |
| Deployment fails on Render |
Incorrect build or start commands |
Ensure the build command is npm install and the start command is node server.js in Render settings. |
| Application not running on Render |
Environment variable HOSTED is not set |
Ensure you have set the HOSTED environment variable to yes in Render settings. |
Error: listen EADDRINUSE: address already in use |
Port 3000 is already in use |
Change the port number in app.listen(PORT) to a different port or stop the process using port 3000 (npx kill-port 3000). |