Paper tries to register Brigadier commands from disabled plugins (causes NPE)

Stack trace

Time: 2025-10-10 15:17:56
Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at io.papermc.paper.command.brigadier.APICommandMeta.plugin(APICommandMeta.java:25)
	at io.papermc.paper.command.brigadier.PaperBrigadier.wrapNode(PaperBrigadier.java:55)
	at io.papermc.paper.command.brigadier.bukkit.BukkitBrigForwardingMap$Values$1.next(BukkitBrigForwardingMap.java:198)
	at io.papermc.paper.command.brigadier.bukkit.BukkitBrigForwardingMap$Values$1.next(BukkitBrigForwardingMap.java:172)
	at java.base/java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1078)
	at org.bukkit.craftbukkit.help.SimpleHelpMap.initializeCommands(SimpleHelpMap.java:127)
	at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:619)
	at net.minecraft.server.MinecraftServer.loadWorld0(MinecraftServer.java:743)
	at net.minecraft.server.MinecraftServer.loadLevel(MinecraftServer.java:488)
	at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:280)
	at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1164)
	at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:310)
	at java.base/java.lang.Thread.run(Thread.java:1583)

Plugin and Datapack List

only my personal plugin.

Actions to reproduce (if known)

see below. you can reproduce with any plugin that uses brigadier and have requirement.

Paper version

[15:17:39] [ServerMain/INFO]: [bootstrap] Loading Paper 1.21.8-60-main@29c8822 (2025-09-06T21:49:13Z) for Minecraft 1.21.8

i can't paste like example because it crashes in bootstrap.
seems every versions on using brigadier.
(occurs on paper-1.21.10-64 too. )

Other

i made a simple Paper plugin that requires Skript.

name: TestPlugin1
version: '1.0-SNAPSHOT'
main: kim.biryeong.testplugin.TestPlugin
api-version: '1.21'
authors: [ biryeongtrain ]
description: test
bootstrapper: kim.biryeong.testplugin.TestPluginBootstrapper
dependencies:
  server:
    Skript:
      load: BEFORE
      required: true
      join-classpath: true

in paper-plugin.yml

package kim.biryeong.testplugin;

import org.bukkit.plugin.java.JavaPlugin;

public final class TestPlugin extends JavaPlugin {

    @Override
    public void onEnable() {
        // Plugin startup logic
    }

    @Override
    public void onDisable() {
        // Plugin shutdown logic
    }
}

in TestPlugin.java

public class TestPluginBootstrapper implements PluginBootstrap {
     private final Logger LOGGER = LoggerFactory.getLogger(TestPluginBootstrapper.class);
    @Override
    public void bootstrap(BootstrapContext bootstrapContext) {
        LOGGER.info("TestPluginBootstrapper bootstrap called");
        bootstrapContext.getLifecycleManager().registerEventHandler(LifecycleEvents.COMMANDS, commands -> {
            LiteralCommandNode<CommandSourceStack> test = Commands.literal("paper-command-test")
                    .build();

            LiteralCommandNode<CommandSourceStack> test_child = Commands.literal("test")
                    .executes(ctx -> {
                        ctx.getSource().getExecutor().sendMessage("Hello World!");
                        return 1;
                    })
                    .build();
            commands.registrar().register(test);
            test.addChild(test_child);
        });
    }
}

in TestPluginBootstrapper.java

and then I just ran Paper without the required dependency.

PaperTest
├── plugins
│   └── testPlugin.jar (paper-plugin that requires Skript. uses brigadier for register its command)
└── paper-1.21.10-64.jar

first, Paper executes the plugin’s bootstrap since it doesn’t have any dependencies during the bootstrap phase.

[15:46:58] [ServerMain/INFO]: [PluginInitializerManager] Paper plugins (1):
 - TestPlugin1 (1.0-SNAPSHOT)
[15:46:58] [ServerMain/INFO]: [kim.biryeong.testplugin.TestPluginBootstrapper] TestPluginBootstrapper bootstrap called

after the server section, Paper disables my test plugin because Skript is missing. (yes, this is not a bug.)

[15:22:30] [Server thread/ERROR]: [ModernPluginLoadingStrategy] Could not load 'plugins\TestPlugin1-1.0-SNAPSHOT.jar' in 'plugins'
org.bukkit.plugin.UnknownDependencyException: Unknown/missing dependency plugins: [Skript]. Please download and install these plugins to run 'TestPlugin1'.
	at io.papermc.paper.plugin.entrypoint.strategy.modern.ModernPluginLoadingStrategy.loadProviders(ModernPluginLoadingStrategy.java:82) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:38) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:39) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:555) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:323) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1230) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:353) ~[paper-1.21.10.jar:1.21.10-64-fba780d]
	at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]

when all plugins are loaded, Paper tries to initialize commands. however, my test plugin’s command also remains queued for registration.

java.lang.NullPointerException: null
	at java.base/java.util.Objects.requireNonNull(Objects.java:233) ~[?:?]
	at io.papermc.paper.command.brigadier.APICommandMeta.plugin(APICommandMeta.java:25) ~[paper-1.21.8.jar:?]
	at io.papermc.paper.command.brigadier.PaperBrigadier.wrapNode(PaperBrigadier.java:55) ~[paper-1.21.8.jar:?]
	at io.papermc.paper.command.brigadier.bukkit.BukkitBrigForwardingMap$Values$1.next(BukkitBrigForwardingMap.java:198) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at io.papermc.paper.command.brigadier.bukkit.BukkitBrigForwardingMap$Values$1.next(BukkitBrigForwardingMap.java:172) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at java.base/java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1078) ~[?:?]
	at org.bukkit.craftbukkit.help.SimpleHelpMap.initializeCommands(SimpleHelpMap.java:127) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:619) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at net.minecraft.server.MinecraftServer.loadWorld0(MinecraftServer.java:743) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at net.minecraft.server.MinecraftServer.loadLevel(MinecraftServer.java:488) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:280) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1164) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:310) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
	at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]

@NullMarked
public record APICommandMeta(@Nullable PluginMeta pluginMeta, @Nullable String description, List<String> aliases, @Nullable String helpCommandNamespace) {

    public APICommandMeta(final @Nullable PluginMeta pluginMeta, final @Nullable String description) {
        this(pluginMeta, description, Collections.emptyList(), null);
    }

    public APICommandMeta {
        aliases = List.copyOf(aliases);
    }

    @Nullable
    public Plugin plugin() {
        return this.pluginMeta == null ? null : Objects.requireNonNull(Bukkit.getPluginManager().getPlugin(this.pluginMeta.getName()));
    }

    public APICommandMeta withAliases(List<String> registeredAliases) {
        return new APICommandMeta(this.pluginMeta, this.description, List.copyOf(registeredAliases), this.helpCommandNamespace);
    }
}

the problem is here: the commands I registered still have a PluginMeta, because they were registered through Paper Brigadier.

however, since my plugin is disabled, it can’t retrieve the Plugin instance.

you can see full log at here : https://mclo.gs/jpynYpe

Start with APICommandMeta.plugin(), PaperBrigadier.wrapNode(), and BukkitBrigForwardingMap.Values, then reproduce the missing-Skript dependency case described in the issue. Trace how the queued Brigadier command reaches SimpleHelpMap.initializeCommands; done means a plugin disabled for a missing dependency no longer causes server startup to throw a NullPointerException.