Strange error message in Node.js

Question

I've been getting a lot of strange error message lately, and now I can't even get app.js started. What could the following mean, and does anyone know how to solve it?

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
TypeError: Cannot read property 'port' of null
    at Object.<anonymous> (/Users/henrikpetersson81/node/last/test4/app.js:15:64)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:31)
    at Function._load (module.js:308:12)
    at Array.0 (module.js:479:10)
    at EventEmitter._tickCallback (node.js:192:40)

Probably a syntax error but we can't help unless you post the code. — Jonathan Rowny, Apr 18 '12 at 13:27
It's a runtime error, not a syntax error. A syntax error would say "SyntaxError". — Peter Lyons, Apr 18 '12 at 13:29
Can you show your code? if you're using Express, be aware that express 3.0 has changed the way it works. — Menztrual, Apr 18 '12 at 13:48

score 4 · Answer 1 · answered Oct 01 '13 at 12:14

4

The port is propably already used. It was with me the case.

answered Oct 01 '13 at 12:14

eeezyy

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score 2 · Accepted Answer · edited May 23 '17 at 12:30

2

Saw a similar question recently. You could be experiencing a similar issue. Perhaps one of the libraries you are using (or your own code) is trying to access app.address().port before the app.listen has completed and the corresponding callback has been invoked.

edited May 23 '17 at 12:30

Community

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answered Apr 18 '12 at 13:28

Peter Lyons

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score 1 · Answer 3 · answered Apr 18 '12 at 14:02

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I found an article explaining the same error message, and it's a problem with the port. I changed the port from 3000 to 5959 and now it works. Strange though that the port suddenly stopped working.

answered Apr 18 '12 at 14:02

holyredbeard

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Do you have another application, perhaps a ruby on rails app, already listening on port 3000? – Peter Lyons Apr 18 '12 at 14:43
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Actually no, so it's kinda strange. – holyredbeard Apr 19 '12 at 18:38
The same is with me! Port 3000 is not busy by other apps but NodeJS can't listen for it. REALLY strange! – Michael Z Jun 05 '14 at 11:33

score 0 · Answer 4 · answered Jan 16 '15 at 09:32

I had the same issue. It turns out while using nodemon( or simple for that matter) when u kill the node server it might not have been killed, so a server is still listening to 3000 port. To overcome this simple close the terminal and restart the server.(On ubuntu machine , using node and Nodemon)

score 0 · Answer 5 · answered Dec 09 '16 at 03:31

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I had a similar issue, where port:3000 is solely used by node.js script. Killing the PID worked for me for port:3000.

lsof -i :3000
kill -9 <PID>

answered Dec 09 '16 at 03:31

Captain Sparrow

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score 0 · Answer 6 · answered Jul 08 '17 at 09:11

the port that your localhost is listening to, is being used by some other application/service. try changing the port at the following location to a different port number like 8888 or 3000 and you should be good to go.

/Users/henrikpetersson81/node/last/test4/app.js

Strange error message in Node.js

6 Answers6