Node EADDRINUSE (Address Already in Use) Error

Every once in a while my Macbook Pro freaks out and a process goes rogue.  This oftentimes happens when I’m working on the excellent debugger.html project; I attempt to start the server side of the debugger and suddenly I’m hit with an error that resembles the following, leading to the process not starting from that time forward:

Error: listen EADDRINUSE at Object._errnoException (util.js:1026:11) at _exceptionWithHostPort (util.js:1049:20) at Server.setupListenHandle [as _listen2] (net.js:1343:14) at listenInCluster (net.js:1391:12) at doListen (net.js:1500:7) at _combinedTickCallback (internal/process/next_tick.js:141:11) at process._tickCallback (internal/process/next_tick.js:180:9) at Function.Module.runMain (module.js:667:11) at startup (bootstrap_node.js:201:16) at bootstrap_node.js:626:3 

The best way to fix this issue is by killing the Node.js process that’s running for the rogue task.  Start by finding a listing of all of the node processes:

ps aux | grep node

You’ll see a listing similar to this:

davidwalsh 12413 0.0 0.0 2592088 3888 ?? S 7:38PM 0:20.45 /Users/davidwalsh/Projects/debugger.html/node_modules/flow-bin/flow-osx-v0.52.0/flow
davidwalsh 12412 0.0 0.0 29739356 2372 ?? S 7:38PM 0:00.12 /Users/davidwalsh/Projects/debugger.html/node_modules/flow-bin/flow-osx-v0.52.0/flow
davidwalsh 12411 0.0 0.0 29732188 2372 ?? S 7:38PM 0:00.07 /Users/davidwalsh/Projects/debugger.html/node_modules/flow-bin/flow-osx-v0.52.0/flow
davidwalsh 12410 0.0 0.0 29732188 2372 ?? S 7:38PM 0:00.07 /Users/davidwalsh/Projects/debugger.html/node_modules/flow-bin/flow-osx-v0.52.0/flow
davidwalsh 12409 0.0 0.0 29731164 2372 ?? S 7:38PM 0:00.06 /Users/davidwalsh/Projects/debugger.html/node_modules/flow-bin/flow-osx-v0.52.0/flow

When you identify the rogue process, use the kill command along with the process number to remove it:

#kill -9 {process_number}
kill -9 12413

With the process killed you can now start up the server as normal!

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