mojira.dev
MC-34749

Hopper: java.lang.IllegalStateException: failed to create a child event loop - Caused by AntiVirus / Firewall software

Resolved
Invalid
10

Moderator Note

  • This issue is most commonly caused by a broken installation of Avast! free edition Anti-virus software. A reinstallation of Avast! and a reboot usually fixes it.

    • McAfee anti-virus software (and derivatives) are also know to cause this issue, and currently the only known solution is to uninstall this software to correct the problem.

    • Also Outpost security may cause that issue.

  • This error also occurs when Java tries to open a socket on the IPv6 stack, but could't get a connection to the outside world. Try forcing the use of the IPv4 stack by adding -Djava.net.preferIPv4Stack=true to the JVM Arguments in your launch installation (to edit your JVM arguments, click "Edit" on the profile you are using, then click "More Options").

Please visit Community Support for further support.

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-294053/

Crash:

java.lang.IllegalStateException: failed to create a child event loop
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:61)
	at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:49)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:61)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52)
	at mo.<init>(SourceFile:36)
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at brh.<init>(SourceFile:38)
	at ays.a(SourceFile:1585)
	at bbs.e(SourceFile:162)
	at bbt.a(SourceFile:214)
	at bam.a(SourceFile:186)
	at bbs.a(SourceFile:187)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Don't do that.

Time: 10.10.13 17:10
Description: Rendering screen

java.lang.IllegalStateException: failed to create a child event loop
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:61)
	at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:49)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:61)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52)
	at mo.<init>(SourceFile:36)
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at brh.<init>(SourceFile:38)
	at ays.a(SourceFile:1585)
	at bbs.e(SourceFile:162)
	at bbt.a(SourceFile:214)
	at bam.a(SourceFile:186)
	at bbs.a(SourceFile:187)
	at bkv.b(SourceFile:851)
	at ays.ab(SourceFile:783)
	at ays.e(SourceFile:706)
	at net.minecraft.client.main.Main.main(SourceFile:103)
Caused by: io.netty.channel.ChannelException: failed to open a new selector
	at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:128)
	at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:120)
	at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:87)
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:57)
	... 15 more
Caused by: java.io.IOException: Unable to establish loopback connection
	at sun.nio.ch.PipeImpl$Initializer.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.nio.ch.PipeImpl.<init>(Unknown Source)
	at sun.nio.ch.SelectorProviderImpl.openPipe(Unknown Source)
	at java.nio.channels.Pipe.open(Unknown Source)
	at sun.nio.ch.WindowsSelectorImpl.<init>(Unknown Source)
	at sun.nio.ch.WindowsSelectorProvider.openSelector(Unknown Source)
	at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:126)
	... 18 more
Caused by: java.net.ConnectException: Connection refused: connect
	at sun.nio.ch.Net.connect(Native Method)
	at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
	at java.nio.channels.SocketChannel.open(Unknown Source)
	... 26 more


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:61)
	at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:49)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:61)
	at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52)
	at mo.<init>(SourceFile:36)
	at net.minecraft.server.MinecraftServer.<init>(SourceFile:114)
	at brh.<init>(SourceFile:38)
	at ays.a(SourceFile:1585)
	at bbs.e(SourceFile:162)
	at bbt.a(SourceFile:214)
	at bam.a(SourceFile:186)
	at bbs.a(SourceFile:187)

-- Screen render details --
Details:
	Screen name: bry
	Mouse location: Scaled: (203, 62). Absolute: (406, 355)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2
Stacktrace:
	at bkv.b(SourceFile:851)
	at ays.ab(SourceFile:783)
	at ays.e(SourceFile:706)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 13w41a
	Operating System: Windows Vista (amd64) version 6.1
	Java Version: 1.6.0_13, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 132615600 bytes (126 MB) / 170655744 bytes (162 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 13w41a
	LWJGL: 2.9.0
	OpenGL: GeForce GT 220/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: [faithful32pack.zip]
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-294053/16540251/

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is duplicated by 589

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584 more links

relates to 2

Comments 62

For me, the same/similar stacktrace/exception was caused also by firewall. In my case Comodo. (I had purposefully blocked javaw.exe, as it can be used by all kinds of software, including those with malign intentions.)

The reason (for my case, normal single-player gaming) why it pops up now is apparently because previously Minecraft used a direct connection within a JRE (running both the single-player server and the client), or at least something else than a network socket, to communicate between the server and the client, but now it apparently wants a real socket, even if it is between the same JRE (or at least the same host). Real socket means network layer firewalls can now catch it. Oops.

I didn't disable/uninstall anything, I just adjusted the firewall's rules to allow outgoing access from javaw.exe. Not ideal (as it would be better if I could get it to block javaw in general, but allow access when the starter of the javaw.exe was minecraft.exe), but the solution shall do for now.

Isn't that pointless that a "Firewall" blocks access to localhost ? Don't get it...

Counter-question would be, isn't it pointless to use a network socket to communicate between two threads (or even processes) of basically the same application running from the same user account?

Typically localhost access should be ok, especially on a typical consumer PC, but there are cases/situations where an application should be blocked from any network connections, including localhost. It is more appropriate that the default of a firewall should be "block all access" for any application that is not specifically allowed to have some access (with installation providing a bunch of rules to have less annoying times figuring out all the operating system processes etc.)

The difference is between occasionally giving permission to an app that for some reason needs it, or never noticing something, possibly nasty, happening.

I'd guess many a firewall has a default rule of allowing localhost access to any process which isn't specifically disallowed to have it, but... it is the compromise between convenience and security. I like to err on the side of security.

I get this bug, trying to open any single-player world. I have Avast antivirus, and have for a couple weeks now. My worlds would load just fine until yesterday, it seemed as though there was server-side lag (block lag, teleporting to previous places, etc.), when playing my single-player worlds. And then, today, I get this error.

Matthew Persil

Windows 7 Version 6.1.7601, Java 7u45

Redirected here from MC-43077. Getting this issue too. Currently using Avast! Premier. Only way I can get the server to run is to disable the firewall.

52 more comments

Hi. I have the same problem, I upgraded to Windows 11 and now I have the same error when entering minecraft. Have you solved this problem? Can you help me?

Después de 20 días buscando la solución encontré la gema preciosa.

Lo unico que tienen que hacer es, descargar java desde este link https://www.oracle.com/java/technologies/downloads/#jdk17-windows

Después lo extraen dentro de su carpeta en C:/Archivosdeprograma/Java , pegan la carpeta que extrajeron ahí, van a su launcher, editan la ruta de path de java, ponen el jawaw.exe que esta dentro de la carpeta y nada, a disfrutar 
After 20 days looking for the solution I found the precious gem.

All you have to do is download java from this link https://www.oracle.com/java/technologies/downloads/#jdk17-windows
Then they extract it into their folder in C: / Program Files / Java, they paste the folder they extracted there, they go to their launcher, they edit the java path, they put the jawaw.exe that is inside the folder and nothing, to to enjoy

i solved check the post

Carlos Sánchez

Hello

I have done all the possible procedures found on the web and I still cannot solve the problem, I have windows 11, but before having windows 11 the problem already existed

Marcin Marcinkowski

as someone wrote above, had to download newest JDK from oracle site and set the java path to it in minecraft launcher

[Bot] Hopper

(Unassigned)

Community Consensus

antivirus, firewall, singleplayer

Minecraft 13w41a, Minecraft 13w41b, Minecraft 13w42b, Minecraft 13w43a, Minecraft 1.7, ..., Minecraft 1.7.4, Minecraft 1.7.5, Minecraft 1.7.9, Minecraft 1.13.2, 1.14.4

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