Start failed on Forge and Vanilla

[oRD-oSS]

Today I faced an issue with my server start.
There is and error [init] [ERROR] Failed to install Forge

Log (click to expand)

[init] Running as uid=1000 gid=1000 with /data as 'drwxr-xr-x 11 1000 1000 4096 Sep 18 12:44 /data'
[init] Image info: buildtime=2025-10-15T01:44:07.146Z,version=java21,revision=d45c931c92bc4a1f5412548c2eb8937c3d95d2a3
[init] Resolving type given FORGE
[mc-image-helper] 17:20:17.387 ERROR : 'install-forge' command failed. Version is 1.50.1
reactor.core.Exceptions$ReactiveException: java.net.UnknownHostException: Failed to resolve 'files.minecraftforge.net' [A(1), AAAA(28)] after 2 queries 
	at reactor.core.Exceptions.propagate(Exceptions.java:410)
	at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:102)
	at reactor.core.publisher.Mono.block(Mono.java:1779)
	at me.itzg.helpers.http.ObjectFetchBuilder.execute(ObjectFetchBuilder.java:42)
	at me.itzg.helpers.forge.ForgeInstallerResolver.loadPromotions(ForgeInstallerResolver.java:121)
	at me.itzg.helpers.forge.ForgeInstallerResolver.resolve(ForgeInstallerResolver.java:47)
	at me.itzg.helpers.forge.ForgeInstaller.install(ForgeInstaller.java:54)
	at me.itzg.helpers.forge.InstallForgeCommand.call(InstallForgeCommand.java:109)
	at me.itzg.helpers.forge.InstallForgeCommand.call(InstallForgeCommand.java:19)
	at picocli.CommandLine.executeUserObject(CommandLine.java:2031)
	at picocli.CommandLine.access$1500(CommandLine.java:148)
	at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2469)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2461)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2423)
	at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2277)
	at picocli.CommandLine$RunLast.execute(CommandLine.java:2425)
	at picocli.CommandLine.execute(CommandLine.java:2174)
	at me.itzg.helpers.McImageHelper.main(McImageHelper.java:176)
	Suppressed: java.lang.Exception: #block terminated with an error
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:104)
		... 16 common frames omitted
Caused by: java.net.UnknownHostException: Failed to resolve 'files.minecraftforge.net' [A(1), AAAA(28)] after 2 queries 
	at io.netty.resolver.dns.DnsResolveContext.finishResolve(DnsResolveContext.java:1150)
	at io.netty.resolver.dns.DnsResolveContext.tryToFinishResolve(DnsResolveContext.java:1097)
	at io.netty.resolver.dns.DnsResolveContext.query(DnsResolveContext.java:455)
	at io.netty.resolver.dns.DnsResolveContext.onResponse(DnsResolveContext.java:662)
	at io.netty.resolver.dns.DnsResolveContext.access$500(DnsResolveContext.java:70)
	at io.netty.resolver.dns.DnsResolveContext$2.operationComplete(DnsResolveContext.java:513)
	at io.netty.util.concurrent.DefaultPromise.notifyListener0(DefaultPromise.java:603)
	at io.netty.util.concurrent.DefaultPromise.notifyListeners0(DefaultPromise.java:596)
	at io.netty.util.concurrent.DefaultPromise.notifyListenersNow(DefaultPromise.java:572)
	at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:505)
	at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:649)
	at io.netty.util.concurrent.DefaultPromise.setSuccess0(DefaultPromise.java:638)
	at io.netty.util.concurrent.DefaultPromise.trySuccess(DefaultPromise.java:118)
	at io.netty.resolver.dns.DnsQueryContext.trySuccess(DnsQueryContext.java:308)
	at io.netty.resolver.dns.DnsQueryContext.finishSuccess(DnsQueryContext.java:299)
	at io.netty.resolver.dns.DnsNameResolver$DnsResponseHandler.channelRead(DnsNameResolver.java:1491)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
	at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:107)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1357)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:868)
	at io.netty.channel.epoll.EpollDatagramChannel.processPacket(EpollDatagramChannel.java:662)
	at io.netty.channel.epoll.EpollDatagramChannel.recvmsg(EpollDatagramChannel.java:697)
	at io.netty.channel.epoll.EpollDatagramChannel.access$300(EpollDatagramChannel.java:56)
	at io.netty.channel.epoll.EpollDatagramChannel$EpollDatagramChannelUnsafe.epollInReady(EpollDatagramChannel.java:536)
	at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:425)
	at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:405)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: io.netty.resolver.dns.DnsErrorCauseException: Query failed with SERVFAIL
	at io.netty.resolver.dns.DnsResolveContext.onResponse(..)(Unknown Source)
[init] [ERROR] Failed to install Forge 

Then I tried to use VANILLA instead of FORGE, and got similar error:

[mc-image-helper] 17:21:39.544 ERROR : 'resolve-minecraft-version' command failed. Version is 1.50.1

reactor.core.Exceptions$ReactiveException: java.net.UnknownHostException: Failed to resolve 'launchermeta.mojang.com' [A(1), AAAA(28)] after 2 queries 

Maybe somebody knows what's the problem?

[itzg]

It's a DNS issue on your system

java.net.UnknownHostException: Failed to resolve 'launchermeta.mojang.com' [A(1), AAAA(28)] after 2 queries

Some common causes are a pihole setup, firewall blocking dns, Docker needs to be reconfigured. Perhaps check your host logs to see if anything there is dns related.

[oRD-oSS]

Thanks a lot for suggestion. I installed updates on my server today and for some reason in updated docker it stops to work. I added dns: 8.8.8.8 to my tailscale config and it works now