React native ERROR Packager can t listen on port 8081

Question

When I run command react-native start  it shows Packager can t listen on port 8081    I know the issue is about software using my port 8081    I use Resource Monitor to see the port  but I can t find 8081  there is no 8081  Can someone show me how to find it

User · Answer

On a mac  run the following command to find id of the process which is using port 8081 sudo lsof -i  8081 Then run the following to terminate process  kill -9 23583  Here is how it will look like

User · Answer

This might be because of McAfee using that port   Doing simple lsof -i 8081 may not show the application and you may have to sudo it   Do sudo lsof -i 8081 and if this command gives an output you can kill it by using sudo launchctl remove com mcafee agent macmn  After this start packager again

User · Answer

in my case  internet on emulator is down as there is no wifi signal on emulator  Resetting emulator has worked

User · Answer

This error is coming because some process is already running on 8081 port  Stop that process and then run your command  it will run your code  For this first list all the process which are using this port by typing    lsof -i  8081     This command will list the process id  PID  of the process and then kill the node process by using    kill -9  lt PID gt      Here PID is the process id of the node process

User · Answer

In order to fix this issue  the process I have mentioned below   Please cancel the current process of   react-native run-android    by CTRL   C or CMD   C  Close metro bundler terminal  window command line which opened automatically   Run the command again on terminal     react-native run-android

User · Answer

Check if there is already a Node server running on your machine and then close it

User · Answer

You can run the packager on another port     react-native start --port 8088   Alternatively  find out what is using which ports on Windows with netstat     netstat -a -b -o   Netstat gives you a PID  which you can use to kill the process     taskkill  pid 1234

User · Answer

First of all  in your device go to Dev  Option -  ADB over Network after do it     adb connect  lt your device adb network gt    react-native run-android     or run-ios  by the way   if this has successfully your device has installed app-debug apk  open app-debug and go to Dev  Settings -  Debug server host  amp  port for device  type in your machine s IP address  generally  System preference -  Network   as in the example below  lt  your machine s IP address   8081  whihout inequality   finally  execute the command below    react-native start --port 8081   try another ports  and verify that you machine and your device are same network

User · Answer

Try to run in another port like 3131  Run the command   react-native run-android --port 3131

User · Answer

You should kill all processes running on port 8081 by kill -9   lsof -i 8081

User · Answer

That picture indeed shows that your 8081 is not in use  If suggestions above haven t helped  and your mobile device is connected to your computer via usb  and you have Android 5 0  Lollipop  or above  you could try     adb reconnect   This is not necessary in most cases  but just in case  let s reset your connection with your mobile and restart adb server  Finally     adb reverse tcp 8081 tcp 8081   So  whenever your mobile device tries to access any port 8081 on itself it will be routed to the 8081 port on your PC   Or  one could try    killall node

User · Answer

Ubuntu Unix  amp  amp  MacOS   My Metro Bundler was stuck and there were lots of node processes running but I didn t have any other development going on besides react-native  so I ran     killall -9 node   The Metro Bundler is running through node on port 8081 by default  and it can encounter issues sometimes whereby it gets stuck  usually due to pressing CTRL S in rapid succession with hot reloading on   If you press CTRL C to kill the react-native run-android process  you will suddenly have a bad time because react-native-run-android will get stuck on    Scanning folders for symlinks in  home poop dev some-app node modules  41ms    Fix     killall -9 node    react-native run-android   Note  if you are developing other apps at the time  killing all the node proceses may interrupt them or any node-based services you have running  so be mindful of the sweeping nature of killall -9  If you aren t running a node-based database or app or you don t mind manually restarting them  then you should be good to go   The reason I leave this detailed answer on this semi-unrelated question is that mine is a solution to a common semi-related problem that sadly requires 2 steps to fix but luckily only takes 2 steps get back to work   If you want to surgically remove exactly the Metro Bundler garbage on port 8081  do the steps in the answer from RC 02  which are     sudo lsof -i  8081    kill -9 23583    where 23583 is the process ID

User · Answer

Take the terminal and type  fuser 8081 tcp   You will get a Process id which is using port 8081 Now kill the process   kill  lt pid gt

[react-native] React native ERROR Packager can't listen on port 8081

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