"Port 4200 is already in use" when running the ng serve command

Solving the "Port 4200 is already in use" Error in Angular CLI

👋 Hey there! Are you learning Angular 2 and encountered the frustrating "Port 4200 is already in use" error when trying to run the ng serve command? Don't worry, you're not alone in this struggle! In this blog post, we'll dive into common issues causing this error and provide you with easy solutions to get you back on track. Let's jump right in! 💪

Understanding the Issue

So, you were able to successfully run the ng serve command and everything was working as expected. But then, when you tried to stop it with Control Z, you encountered the "Port 4200 is already in use" error upon running ng serve again. What gives? 🤔

The Culprit: Zombie Processes

When you stopped the ng serve command using Control Z, it actually creates a zombie process in the background. This zombie process is still holding onto Port 4200, which prevents you from running ng serve again without encountering the port in use error.

Solution 1: Terminating the Zombie Process

Now that we know what's causing the error, let's terminate that pesky zombie process! ❌🧟

1. Open your terminal and execute the ps command to get a list of all running processes.

2. Look for the process ID (PID) associated with the ng serve command. It might have a name like node or ng.

3. Once you have the PID, execute the kill <PID> command to forcefully terminate the process. For example, if the PID is 12345, you would run kill 12345.

4. After successfully terminating the process, you should be able to run ng serve again without encountering the port in use error. 🎉

Solution 2: Using a Different Port

If Solution 1 didn't work for you, there's another workaround you can try: using a different port for your Angular CLI application. 🔀

1. Open the angular.json file located in the root directory of your project.

2. Search for the "serve" configuration under "architect" > "options" > "port". It should be set to "4200".

3. Change the port number to a different value that is not being used by any other application on your system. For example, you can set it to "4300".

4. Save the file and run ng serve again. Your Angular CLI application should now be running on the newly assigned port.

📣 Share Your Success Story!

Congrats on resolving the "Port 4200 is already in use" error! We hope one of the solutions provided above worked for you. Now it's your turn to engage with us! Share your success story in the comments below or on our social media channels. Did you encounter any other challenges while learning Angular CLI? Let us know so we can help! 🎉💬

Happy coding! 💻✨