The error that appears me in Minecraft -> Internal Exception: Java.IOException: Se ha forzado la interrupción de una conexión existente por el host remoto. (it appears in spanish, i've changed the language to english but it appears in spanish too)

Quote

[10Aug2021 13:40:32.764] [User Authenticator #2/INFO] [net.minecraft.network.login.ServerLoginNetHandler/]: UUID of player ItsCogoMC is ------------------------------------------------
[10Aug2021 13:40:40.047] [Server thread/INFO] [net.minecraft.server.management.PlayerList/]: ItsCogoMC[/-----------------] logged in with entity id 219 at (-487.5, 71.0, 567.5)
[10Aug2021 13:40:40.068] [Server thread/FATAL] [net.minecraftforge.fml.loading.RuntimeDistCleaner/DISTXFORM]: Attempted to load class net/minecraft/client/Minecraft for invalid dist DEDICATED_SERVER
[10Aug2021 13:40:40.069] [Server thread/WARN] [net.minecraft.network.NetworkSystem/]: Failed to handle packet for /77.225.157.85:63774
java.lang.RuntimeException: Attempted to load class net/minecraft/client/Minecraft for invalid dist DEDICATED_SERVER
    at net.minecraftforge.fml.loading.RuntimeDistCleaner.processClassWithFlags(RuntimeDistCleaner.java:71) ~[forge-1.16.5-36.2.2.jar:36.2]
    at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) ~[modlauncher-8.0.9.jar:?]
    at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:120) ~[modlauncher-8.0.9.jar:?]
    at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:265) ~[modlauncher-8.0.9.jar:?]
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:136) ~[modlauncher-8.0.9.jar:?]
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) ~[modlauncher-8.0.9.jar:?]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[?:1.8.0_292]
    at jeresources.profiling.ProfileCommand.lambda$register$0(ProfileCommand.java:26) ~[jeresources:0.12.1.127]
    at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.lambda$test$0(RankCommandPredicate.java:41) ~[ftbranks:?]
    at dev.ftb.mods.ftbranks.api.OptionalBoolean.orElseGet(OptionalBoolean.java:58) ~[ftbranks:?]
    at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.test(RankCommandPredicate.java:41) ~[ftbranks:?]
    at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.test(RankCommandPredicate.java:15) ~[ftbranks:?]
    at com.mojang.brigadier.tree.CommandNode.canUse(CommandNode.java:66) ~[?:?]
    at net.minecraft.command.Commands.func_197052_a(Commands.java:279) ~[?:?]
    at net.minecraft.command.Commands.func_197051_a(Commands.java:273) ~[?:?]
    at net.minecraft.server.management.PlayerList.func_187245_a(PlayerList.java:597) ~[?:?]
    at net.minecraft.server.management.PlayerList.func_187243_f(PlayerList.java:491) ~[?:?]
    at net.minecraft.server.management.PlayerList.func_72355_a(PlayerList.java:162) ~[?:?]
    at net.minecraft.network.login.ServerLoginNetHandler.func_147326_c(ServerLoginNetHandler.java:118) ~[?:?]
    at net.minecraft.network.login.ServerLoginNetHandler.func_73660_a(ServerLoginNetHandler.java:65) ~[?:?]
    at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:222) ~[?:?]
    at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:134) ~[?:?]
    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:865) ~[?:?]
    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:291) ~[?:?]
    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:787) ~[?:?]
    at net.minecraft.server.MinecraftServer.func_240802_v_(MinecraftServer.java:642) ~[?:?]
    at net.minecraft.server.MinecraftServer.func_240783_a_(MinecraftServer.java:232) ~[?:?]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_292]
[10Aug2021 13:40:41.042] [Server thread/INFO] [net.minecraft.network.play.ServerPlayNetHandler/]: ItsCogoMC lost connection: Internal server error
[10Aug2021 13:40:41.042] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer/]: ItsCogoMC left the game
[10Aug2021 13:41:01.092] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer/]: There are 0 of a max of 500 players online: 
[10Aug2021 13:41:35.193] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer/]: There are 0 of a max of 500 players online: 
 

 

PD: Forge Mod Loader, Forge Server, 1.16.5 and it appears after "Loading Terrain"

This appears in My Console 

Quote

10.08 13:52:58 [Server] User Authenticator #5/INFO UUID of player ItsCogoMC is ------------------------------------------------
10.08 13:53:06 [Connect] User ItsCogoMC, IP --------------
10.08 13:53:06 [Multicraft] ItsCogoMC ran command Message of the Day
10.08 13:53:06 [Server] Server thread/FATAL [ne.mi.fm.lo.RuntimeDistCleaner/DISTXFORM]: Attempted to load class net/minecraft/client/Minecraft for invalid dist DEDICATED_SERVER
10.08 13:53:06 [Server] Server thread/WARN Failed to handle packet for /----------------------
10.08 13:53:06 [Server] INFO java.lang.RuntimeException: Attempted to load class net/minecraft/client/Minecraft for invalid dist DEDICATED_SERVER
10.08 13:53:06 [Server] INFO at net.minecraftforge.fml.loading.RuntimeDistCleaner.processClassWithFlags(RuntimeDistCleaner.java:71) ~[forge-1.16.5-36.2.2.jar:36.2] {}
10.08 13:53:06 [Server] INFO at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) ~[modlauncher-8.0.9.jar:?] {}
10.08 13:53:06 [Server] INFO at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:120) ~[modlauncher-8.0.9.jar:?] {}
10.08 13:53:06 [Server] INFO at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:265) ~[modlauncher-8.0.9.jar:?] {}
10.08 13:53:06 [Server] INFO at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:136) ~[modlauncher-8.0.9.jar:?] {re:classloading}
10.08 13:53:06 [Server] INFO at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) ~[modlauncher-8.0.9.jar:?] {re:classloading}
10.08 13:53:06 [Server] INFO at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[?:1.8.0_292] {}
10.08 13:53:06 [Server] INFO at jeresources.profiling.ProfileCommand.lambda$register$0(ProfileCommand.java:26) ~[jeresources:0.12.1.127] {re:classloading}
10.08 13:53:06 [Server] INFO at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.lambda$test$0(RankCommandPredicate.java:41) ~[ftbranks:?] {re:classloading}
10.08 13:53:06 [Server] INFO at dev.ftb.mods.ftbranks.api.OptionalBoolean.orElseGet(OptionalBoolean.java:58) ~[ftbranks:?] {re:classloading}
10.08 13:53:06 [Server] INFO at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.test(RankCommandPredicate.java:41) ~[ftbranks:?] {re:classloading}
10.08 13:53:06 [Server] INFO at dev.ftb.mods.ftbranks.impl.RankCommandPredicate.test(RankCommandPredicate.java:15) ~[ftbranks:?] {re:classloading}
10.08 13:53:06 [Server] INFO at com.mojang.brigadier.tree.CommandNode.canUse(CommandNode.java:66) ~[?:?] {re:classloading}
10.08 13:53:06 [Server] INFO at net.minecraft.command.Commands.func_197052_a(Commands.java:279) ~[?:?] {re:mixin,re:classloading,pl:mixin:APP:ftbranks-common.mixins.json:CommandsMixin,pl:mixin:A}
10.08 13:53:06 [Server] INFO at net.minecraft.command.Commands.func_197051_a(Commands.java:273) ~[?:?] {re:mixin,re:classloading,pl:mixin:APP:ftbranks-common.mixins.json:CommandsMixin,pl:mixin:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.management.PlayerList.func_187245_a(PlayerList.java:597) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:betterendforge.mixins.json:PlayerListMixin,pl:mixin:APP:endergetic.mixins.json:PlayerListMixin,pl:mixin:APP:assets/botania/botania.mixins.json:MixinPlayerList,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.management.PlayerList.func_187243_f(PlayerList.java:491) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:betterendforge.mixins.json:PlayerListMixin,pl:mixin:APP:endergetic.mixins.json:PlayerListMixin,pl:mixin:APP:assets/botania/botania.mixins.json:MixinPlayerList,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.management.PlayerList.func_72355_a(PlayerList.java:162) ~[?:?] {re:mixin,pl:runtimedistcleaner:A,re:classloading,pl:mixin:APP:betterendforge.mixins.json:PlayerListMixin,pl:mixin:APP:endergetic.mixins.json:PlayerListMixin,pl:mixin:APP:assets/botania/botania.mixins.json:MixinPlayerList,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.network.login.ServerLoginNetHandler.func_147326_c(ServerLoginNetHandler.java:118) ~[?:?] {re:classloading}
10.08 13:53:06 [Server] INFO at net.minecraft.network.login.ServerLoginNetHandler.func_73660_a(ServerLoginNetHandler.java:65) ~[?:?] {re:classloading}
10.08 13:53:06 [Server] INFO at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:222) ~[?:?] {re:classloading,pl:runtimedistcleaner:A,re:mixin,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:134) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:865) ~[?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:mixin:APP:betterendforge.mixins.json:MinecraftServerMixin,pl:mixin:APP:kubejs-common.mixins.json:MinecraftServerMixin,pl:mixin:APP:byg.mixins.json:server.MixinMinecraftServer,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:291) ~[?:?] {re:classloading,pl:accesstransformer:B}
10.08 13:53:06 [Server] INFO at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:787) ~[?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:mixin:APP:betterendforge.mixins.json:MinecraftServerMixin,pl:mixin:APP:kubejs-common.mixins.json:MinecraftServerMixin,pl:mixin:APP:byg.mixins.json:server.MixinMinecraftServer,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:06 [Server] INFO at net.minecraft.server.MinecraftServer.func_240802_v_(MinecraftServer.java:642) ~[?:?] {re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:classloading,pl:accesstransformer:B,pl:mixin:APP:betterendforge.mixins.json:MinecraftServerMixin,pl:mixin:APP:kubejs-common.mixins.json:MinecraftServerMixin,pl:mixin:APP:byg.mixins.json:server.MixinMinecraftServer,pl:mixin:A,pl:runtimedistcleaner:A}
10.08 13:53:07 [Multicraft] Skipped 2 lines due to rate limit (30/s)
10.08 13:53:07 [Disconnect] User ItsCogoMC has disconnected, reason: Internal server error
10.08 13:53:07 [Server] Server thread/INFO ItsCogoMC left the game

 

Ok