The game crashed whilst mouseclicked event handler Error: java.lang.IllegalStateException: failed to create a child event loop

Hi, the issue your having a problem with is a duplicate of MC-34749

There is a moderator note explaining how to fix this issue, maybe this will help you

Personally, i added -Djava.net.preferIPv4Stack=true to the JVM Arguments and it fixed the issue

I dont use any anti-virus software and i removed the JVM Argument and added in -Djava.net.preferIPv4Stack=true but no luck was found doing that.

Here is a copy of the crash report, if that could be any help:

Minecraft Crash Report -------- Minecraft Crash Report ----// Shall we play a game?
Time: 7/6/19 8:45 PMDescription: mouseClicked event handler
java.lang.IllegalStateException: failed to create a child event loop at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:88) at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:58) at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:47) at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:59) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:77) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:72) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:59) at vz.f(SourceFile:55) at vz$$Lambda$2333/1919800167.get(Unknown Source) at zs.a(SourceFile:16) at vz.a(SourceFile:136) at cvo.a(SourceFile:1640) at ddc.c(SourceFile:251) at ddc.b(SourceFile:173) at ddc$$Lambda$1779/721863560.onPress(Unknown Source) at cwu.onPress(SourceFile:18) at cwp.onClick(SourceFile:15) at cws.mouseClicked(SourceFile:154) at cxp.mouseClicked(SourceFile:27) at cvp.b(SourceFile:86) at cvp$$Lambda$1750/798555759.run(Unknown Source) at czx.wrapScreenError(SourceFile:441) at cvp.a(SourceFile:86) at cvp$$Lambda$1459/1772874516.invoke(Unknown Source) at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36) at org.lwjgl.system.JNI.invokeV(Native Method) at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101) at cuh.l(SourceFile:425) at cuh.c(SourceFile:283) at cvo.b(SourceFile:1023) at cvo.e(SourceFile:976) at cvo.b(SourceFile:411) at net.minecraft.client.main.Main.main(SourceFile:154)Caused by: io.netty.channel.ChannelException: failed to open a new selector at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:177) at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:151) at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:127) at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:36) at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:84) ... 32 moreCaused by: java.io.IOException: Unable to establish loopback connection at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:101) at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:68) at java.security.AccessController.doPrivileged(Native Method) at sun.nio.ch.PipeImpl.<init>(PipeImpl.java:170) at sun.nio.ch.SelectorProviderImpl.openPipe(SelectorProviderImpl.java:50) at java.nio.channels.Pipe.open(Pipe.java:155) at sun.nio.ch.WindowsSelectorImpl.<init>(WindowsSelectorImpl.java:127) at sun.nio.ch.WindowsSelectorProvider.openSelector(WindowsSelectorProvider.java:44) at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:175) ... 36 moreCaused by: java.net.ConnectException: Connection timed out: connect at sun.nio.ch.Net.connect0(Native Method) at sun.nio.ch.Net.connect(Net.java:458) at sun.nio.ch.Net.connect(Net.java:450) at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:648) at java.nio.channels.SocketChannel.open(SocketChannel.java:189) at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(PipeImpl.java:130) at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:83) ... 44 more

A detailed walkthrough of the error, its code path and all known details is as follows:---------------------------------------------------------------------------------------
– Head --Thread: Client threadStacktrace: at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:88) at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:58) at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:47) at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:59) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:77) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:72) at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:59) at vz.f(SourceFile:55) at vz$$Lambda$2333/1919800167.get(Unknown Source) at zs.a(SourceFile:16) at vz.a(SourceFile:136) at cvo.a(SourceFile:1640) at ddc.c(SourceFile:251) at ddc.b(SourceFile:173) at ddc$$Lambda$1779/721863560.onPress(Unknown Source) at cwu.onPress(SourceFile:18) at cwp.onClick(SourceFile:15) at cws.mouseClicked(SourceFile:154) at cxp.mouseClicked(SourceFile:27) at cvp.b(SourceFile:86) at cvp$$Lambda$1750/798555759.run(Unknown Source)
– Affected screen --Details: Screen name: ddcStacktrace: at czx.wrapScreenError(SourceFile:441) at cvp.a(SourceFile:86) at cvp$$Lambda$1459/1772874516.invoke(Unknown Source) at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36) at org.lwjgl.system.JNI.invokeV(Native Method) at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101) at cuh.l(SourceFile:425) at cuh.c(SourceFile:283) at cvo.b(SourceFile:1023) at cvo.e(SourceFile:976) at cvo.b(SourceFile:411) at net.minecraft.client.main.Main.main(SourceFile:154)
– System Details --Details: Minecraft Version: 1.14.3 Operating System: Windows 8.1 (amd64) version 6.3 Java Version: 1.8.0_51, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation Memory: 1467645528 bytes (1399 MB) / 2046820352 bytes (1952 MB) up to 2147483648 bytes (2048 MB) JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M Launched Version: 1.14.3 LWJGL: 3.2.2 build 10 OpenGL: AMD Radeon (TM) R9 380 Series GL version 4.5.13537 Compatibility Profile Context 24.20.13001.1010, ATI Technologies Inc. GL Caps: Using GL 1.3 multitexturing.Using GL 1.3 texture combiners.Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.Shaders are available because OpenGL 2.1 is supported.VBOs are available because OpenGL 1.5 is supported.
Using VBOs: Yes Is Modded: Probably not. Jar signature remains and client brand is untouched. Type: Client (map_client.txt) Resource Packs:  Current Language: English (US) CPU: 4x Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz

I HAVE FOUND A SOLUTION FOR THIS:

• Go to windows defender settings

• Then go to firewall & network protection

• Disable private network (active)

• This has happened to other previous games i have played

HOPE THIS HELPS ANYONE WHO HAS THE SAME ISSUE