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In IntelliJ IDEA Community Edition 14.0.2, I'm trying to run Java Applet and every time I try to run project, I got this this dummy error.

Error: Failed to create a child event loop

What I've tried

  1. Compiling newly created Hello World program
  2. Update IntelliJ
  3. Uninstall & Reinstall
  4. Allow from Windows Firewall rule
  5. Disabling Antivirus Program

I'm using Windows 8.1 with Anti-virus program Windows Defender.

Error detail from Log file:

java.lang.IllegalStateException: failed to create a child event loop
    at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:81)
    at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:50)
    at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:72)
    at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:58)
    at org.jetbrains.io.BuiltInServer.start(BuiltInServer.java:60)
    at org.jetbrains.ide.BuiltInServerManagerImpl$1.run(BuiltInServerManagerImpl.java:111)
    at com.intellij.openapi.application.impl.ApplicationImpl$8.run(ApplicationImpl.java:405)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
    at org.jetbrains.ide.PooledThreadExecutor$1$1.run(PooledThreadExecutor.java:56)
Caused by: io.netty.channel.ChannelException: failed to open a new selector
    at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:127)
    at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:119)
    at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:97)
    at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:31)
    at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:77)
    ... 12 more
Caused by: java.io.IOException: Unable to establish loopback connection
    at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:101)
    at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:68)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.nio.ch.PipeImpl.<init>(PipeImpl.java:170)
    at sun.nio.ch.SelectorProviderImpl.openPipe(SelectorProviderImpl.java:50)
    at java.nio.channels.Pipe.open(Pipe.java:155)
    at sun.nio.ch.WindowsSelectorImpl.<init>(WindowsSelectorImpl.java:127)
    at sun.nio.ch.WindowsSelectorProvider.openSelector(WindowsSelectorProvider.java:44)
    at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:125)
    ... 16 more
Caused by: java.net.SocketException: Network is unreachable: connect
    at sun.nio.ch.Net.connect0(Native Method)
    at sun.nio.ch.Net.connect(Net.java:457)
    at sun.nio.ch.Net.connect(Net.java:449)
    at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:647)
    at java.nio.channels.SocketChannel.open(SocketChannel.java:189)
    at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(PipeImpl.java:130)
    at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:83)
    ... 24 more
Adnan Umer
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  • sometimes i get this error and simply re-run and it disappears. once, i had to restart my PC to get rid of this error. i think it's a bug in intellij - [Issue Link](https://youtrack.jetbrains.com/issue/IDEA-123132) – Don Barry Dec 17 '14 at 19:52
  • I have a similar error with pycharm – Charlie Parker Dec 02 '20 at 20:12

7 Answers7

7

Restarting intelliJ did not help, restarting machine did!

Preeti Joshi
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4

Disable firewall or add idea.exe full correct path to outgoing connect rules of your firewall.
It helped me with IDEA 14.0.3

RoutesMaps.com
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2

I encountered same error when we deploy our application to a Windows Server, however, this server has no antivirus software and the firewall is disabled. In our case, it's due to the Astrill VPN, if we disable the Astrill VPN, the issue would disappear.

derek.z
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0

My os is Windows, Use Pycharm 2017.3 to run scrapy project encountered a similar problem. Today, Use Intellij Idea 2016.3.5 to run spring project had the same question. In my os, Close the Windows Defender can solve this question.

JackDan9
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We have to turn off the firewall. It solves the problem. Even in "eclipse" software also turning off the firewall works well.

Mazumdar Meghamala
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0

updating pycharm to a newer version worked for me and then restarting the pycharm ide.

Charlie Parker
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0

MacOS bigsur 11.7.3. This seems like pycharms bug.I tried close the project and reopen it, doesn't work.And when I totally shutdown pycharm(quit from memory) and start it, everything is fine.(I don't think it is necessary yo reboot your computer.It is a bug about pychar, not your pc)

Skipper
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