ExpressJS - throw er Unhandled error event

Question

I created expressjs application using the following commands   express -e folderName npm install ejs --save npm install   When I run the application with  node app js  I have the following errors   events js 72     throw er     Unhandled  error  event             Error  listen EADDRINUSE     at errnoException  net js 884 11      at Server  listen2  net js 1022 14      at listen  net js 1044 10      at Server listen  net js 1110 5      at Object  lt anonymous gt   folderName app js 33 24      at Module  compile  module js 456 26      at Object Module  extensions  js  module js 474 10      at Module load  module js 356 32      at Function Module  load  module js 312 12      at Function Module runMain  module js 497 10    How to fix it

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None of the answers worked for me   When I restarted my computer I could get the server up and running    Mac     shutdown now -r  Linux     sudo shutdown now -r

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We do get similar error when we sometimes run our express app  We have to follow the same in that case  We need to check if its running in any terminal   If you want to find and kill process  follow these steps    ps aux   grep node Find the process ID  second from the left   kill -9 PRCOCESS ID    OR  Use a single command to close all the running node processes   ps aux   awk   node  print  2     xargs kill -9

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IF it is in mac then it s all about IP of x86 64-apple-darwin13 4 0  If you follow errors it would be something related to x86 64-apple-darwin13 4 0  Add  127 0 0 1       x86 64-apple-darwin13 4 0  to  etc hosts file  Then the problem is gone

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In my case the issue was caused by forgetting to call next   in an expressjs  use  method call       If the current middleware does not end the request-response cycle  it must call next   to pass control to the next middleware  otherwise the request will be left hanging    http   expressjs com guide using-middleware html

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Actually Ctrl C keys not releasing port used by node process  So there is this error  The resolution to the issue was using following code snippet in server js   process on  SIGINT   function       console log    nGracefully shutting down from SIGINT  Ctrl-C           some other closing procedures go here   process exit 1         This worked for me   You can also check for other solutions mentioned at Graceful shutdown in NodeJS

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An instance is probably still running  This will fix it   killall node   Update  This command will only work on Linux Ubuntu  amp  Mac

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events js 183 throw er     Unhandled  error  event   I also got the same kind of problem and tried many ways but finally got this  this works well   npm install ws 3 3 2 --save-dev --save-exact   Refer to this link for more clarifications https   github com ionic-team ionic-cli issues 2922

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In-order to fix this  terminate or close the server you are running  If you are using Eclipse IDE  then follow this  Run  gt  Debug  Right-click the running process and click on Terminate

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I ran into the same issue today and the port was not used  The following approach helped   rm -rf node modules  amp  amp  npm cache clean  amp  amp  npm install npm start

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If you want to use the same port number then type kill   in the terminal  which kills the current background process and frees up the port for further usage

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If you re on Linux  this problem can also occur if Nodejs is not running as root   Change from this   nodejs  path to script js   To this   sudo nodejs  path to script js   Just happened to me and none of the other suggestions here fixed it   Luckily I remembered the script was working the other day when running as root   Hope this helps someone   Disclaimer  This probably isn t the best solution for a production environment   Starting your service as root may introduce some security holes to your server application  In my case  this was a solution for a local service  but I d encourage others to spend some more time trying to isolate the cause

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I fixed the bug by changing the port which was   app set  port   process env PORT    3000   lt br gt    and changed to   app set  port   process env PORT    8080   lt br gt

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this means your file is running now  just enter below code and try again   sudo pkill node

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The port you are listening to is already being listened by another process   When I faced to this error I killed the process using Windows PowerShell  because I used Windows    List itemopen the windows powershell type ps and then you can get list of processes find the process named node  and note the Id type Stop-process  lt Id gt  I think that it is help for windows users

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If you using windows  then you can end process from task manager for node js

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Try the below fixes    Try to close the process that is using your port      netstat -tulnp   grep  lt port number gt   Installing the below pakcage fixed it for me forever       npm install ws 3 3 2 --save-dev --save-exact  Run this command in your terminal       echo fs inotify max user watches 524288   sudo tee -a  etc sysctl conf  amp  amp  sudo sysctl -p   For Arch Linux add this line to  etc sysctl d 99-sysctl conf   fs inotify max user watches 524288  Then execute   sysctl --system  This will also persist across reboots   https   github com guard listen wiki Increasing-the-amount-of-inotify-watchers the-technical-details

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If you ve tried killing all node instances and other services listening on 3000  the default used by the express skeleton setup  to no avail  you should check to make sure that your environment is not defining  port  to be something unexpected  Otherwise  you ll likely get the same error  In the express skeleton s app js file you ll notice line 15   app set  port   process env PORT    3000

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You had run another server use the same port like 8080   Maybe you had run node app in other shell  Please close it and run again   You can check PORT no  is available or not using  netstat -tulnp   grep  lt port no gt    Alternatively  you can use lsof   lsof -i   lt port no gt

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The port Node is trying to use can be already used by another program  In my case it was ntop  which I had recently installed  I had to open http   localhost 3000  in a browser to realize it  Another way to find the process is given here

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npm install --save --save-exact react-scripts 2 1

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Close any other node servers that are running  even if they are in other terminal windows or running on different ports  That should fix the problem

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This worked for me   http   www codingdefined com 2015 09 how-to-solve-nodejs-error-listen html  Just change the port number from the Project properties

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Stop the service that is using that port   sudo service NAMEOFSERVICE stop

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- check what   s running on port 8080 or what ever port u want to check  lsof -i  localhost 8080   if something is running u can close it or use some kill command to close it

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My answers is one of the solution If you are trying to run angular application with below command ng serve --open  --open Opens the url in default browser this tag is causing the issue  i don t know what is the purpose after angular 10 version which is not working  I am still analysing

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You can also change the port from Gruntfile js and run again

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Simple just check your teminal in Visual Studio Code Because me was running my node app and i hibernate my laptop then next morning i turn my laptop on back to development of software  THen i run the again command nodemon app js First waas running from night and the second was running my latest command so two command prompts are listening to same ports that s why you are getting this issue  Simple Close one termianl or all terminal then run your node app js or nodemon app js

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I had the same problem and I found out  that a nodejs process that I had previously canceled with CTRL C was still running  The problem in Windows 10 is  that Ctrl   C Doesn t Kill Gracefully nodejs  I opened the task manager and killed the process manually  The solutions provided on GitHub didn t work for me

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This is because the port you are using to run the script is already in use  You have to stop all other nodes which are using that post  for that  you can check all node by   ps -e   OR for node process only use ps -ef   grep node This will give you the list of all node process with id   to Kill all node process  sudo killall -9 node   Or for the specific id sudo kill -9 id

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In my case I ve had to run vagrant reload as well  Even with no node processes running my express app in my virtual machine I was still getting this error until reloading the vagrant box

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Reason for this error     Some other process is already running on the port  you have specified   Simple and Quick solution  On Linux OS  For example you have specified 3000 as the port    Open the terminal and run lsof -i  3000  If any process is already running on  port 3000 then you will see this printing on the console     x000D   x000D  COMMAND   PID  USER   FD   TYPE DEVICE SIZE OFF NODE NAME x000D  node    16615 aegon   13u  IPv6 183768      0t0  TCP   3000  LISTEN  x000D   x000D   x000D     Copy the PID  process ID  from the output  Run sudo kill -9 16615  you have to put PID after -9   Start the server again

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Just change your port might be your current port is in use by iis or some other server

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After killing the same process multiple times and not being able to locate what else was running on port 8000  I realized I was trying to run on port 8000 twice   Before   MongoClient connect db url   err  database    gt      if  err  return console log err     require    app routes   app  database      app listen port       gt        console log  We are live on     port              require    app routes   app       app listen port       gt      console log  We are live on     port         After   MongoClient connect db url   err  database    gt      if  err  return console log err     require    app routes   app  database      app listen port       gt        console log  We are live on     port              require    app routes   app

[node.js] ExpressJS - throw er Unhandled error event

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