Solving Nodemon Error: Listen EADDRINUSE Address Already in Use Port 5000

The “nodemon error listen EADDRINUSE: address already in use 5000” occurs in Node.js development when the port 5000 is already occupied by another process. This error prevents the server from starting because it can’t bind to the specified port. It’s a common issue that developers encounter when they forget to stop a previous instance of the server or when another application is using the same port.

Causes of the Error

The primary causes of the ‘nodemon error listen EADDRINUSE address already in use 5000′ are:

1. Another process is using port 5000: This is the most common cause. Another application or instance of your Node.js server is already running on port 5000.
2. Multiple instances of the same application: If you accidentally start multiple instances of your application, they will compete for the same port.
3. Zombie processes: Sometimes, processes do not terminate correctly and continue to occupy the port.
4. Network conflicts: Rarely, network configurations or conflicts can cause this error.

Identifying the Problem

To identify the ‘nodemon error listen EADDRINUSE address already in use 5000′, follow these steps:

1. Check Running Processes on Port 5000:

   lsof -i :5000
   

   This command lists all processes using port 5000.

2. Find the Process ID (PID):
   Look for the PID in the output of the above command.

3. Kill the Process:

   kill -9 <PID>
   

   Replace <PID> with the actual PID from the previous step.

4. Restart Nodemon:

   nodemon server.js
   

These commands help you identify and resolve the error by freeing up the port.

Solutions to the Error

Sure, here are the step-by-step solutions:

Stopping the Conflicting Process

1. Find the Process ID (PID) Using the Port:

   • Windows:

     netstat -ano | findstr :5000
     

   • macOS/Linux:

     lsof -i :5000
     

2. Kill the Process:

   • Windows:

     taskkill /PID <PID> /F
     

   • macOS/Linux:

     kill -9 <PID>
     

Changing the Port

1. Open Your Server File (e.g., server.js):

   const PORT = process.env.PORT || 5000;
   

2. Change the Port Number:

   const PORT = process.env.PORT || 3000;
   

3. Restart Your Server:

   nodemon server.js
   

These steps should help you resolve the EADDRINUSE error.

Preventing Future Occurrences

Here are some tips to prevent the ‘nodemon error listen EADDRINUSE address already in use 5000′:

1. Dynamic Port Assignment: Use a dynamic port by setting the port number from an environment variable:

   const port = process.env.PORT || 5000;
   app.listen(port, () => console.log(`Server running on port ${port}`));
   

2. Kill the Process: If the port is already in use, kill the process using it:

   kill -9 $(lsof -t -i:5000)
   

3. Check for Running Processes: Before starting your server, check if the port is in use:

   lsof -i :5000
   

4. Use a Different Port: If port 5000 is frequently in use, consider using a different port:

   const port = 3000;
   app.listen(port, () => console.log(`Server running on port ${port}`));
   

5. Restart Nodemon: Sometimes, simply restarting nodemon can resolve the issue:

   nodemon --exec "killall node && nodemon"
   

These steps should help you avoid the error in future projects.

The ‘nodemon error listen EADDRINUSE: address already in use 5000’

occurs when another process is using port 5000, preventing the server from starting.

To resolve this issue, identify and kill the conflicting process or change the port number. Proper port management is crucial to avoid this error.

Key points include:

• Checking running processes on port 5000
• Finding and killing the PID
• Changing the port number in your server file
• Restarting nodemon

Dynamic port assignment, killing the process, checking for running processes, using a different port, and restarting nodemon are also effective solutions.

By following these steps, developers can prevent this error from occurring in future projects.