Failed to create a child event loop

Question

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

Answer 1

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.

Answer 2

Restarting intelliJ did not help, restarting machine did!

Answer 3

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