When working with local development servers, a message like this might look familiar:

Error: listen EADDRINUSE: address already in use
    at Server.setupListenHandle [as _listen2] (net.js:1300:14)
    at listenInCluster (net.js:1348:12)
    at doListen (net.js:1487:7)
    at processTicksAndRejections (internal/process/task_queues.js:81:21)

This doesn’t really give us much information to work with. Since I couldn’t find a solution on the web within a few minutes, this is my contribution for anyone running into the same problem.

The solution

First, we need to find out what process is causing the problem. We will use the lsof -i command for this. What it does, according to the manual:

selects the listing of files any of whose Internet address matches the address specified to see what application is running on the port

So since the error specifies the application is running on port 8888, we can run:

lsof -i tcp:8888

This outputs:

node    11975 user   29u  IPv4 0x64ffe67f1d4a089      0t0  TCP localhost:ddi-tcp-1 (LISTEN)

We’ve learned that Node.js is the troublemaker here. Instead of shutting down Node.js entirely, we can just terminate the problematic process by using the PID (11975):

kill -9 11975

Now you should be able to run your development server without any problems.