Server crashes with NoSuchMethodError on player join (Fabric 1.21.11, class_2168.method_9259)

[sebastianzehner]

Description

The server crashes reliably whenever a player joins. The error occurs reproducibly on every login, regardless of the player.

Steps to Reproduce

1. Start a Fabric server with Plan 5.7 (build 3306)
2. A player connects
3. Server crashes immediately

Expected Behavior

Player should be able to connect normally without a server crash.

Crash Report

---- Minecraft Crash Report ----
// Why did you do that?
Time: 2026-07-03 22:06:53
Description: Exception in server tick loop
java.lang.NoSuchMethodError: 'boolean net.minecraft.class_2168.method_9259(int)'
        at knot//net.playeranalytics.plan.commands.FabricCommandManager.checkPermission(FabricCommandManager.java:60)
        at knot//net.playeranalytics.plan.commands.FabricCommandManager.lambda$buildCommand$3(FabricCommandManager.java:147)
        at knot//com.mojang.brigadier.tree.CommandNode.canUse(CommandNode.java:65)
        at knot//net.minecraft.class_2170.method_9239(class_2170.java:449)
        at knot//net.minecraft.class_2170.method_9241(class_2170.java:443)
        at knot//net.minecraft.class_3324.method_14596(class_3324.java:592)
        at knot//net.minecraft.class_3324.method_14576(class_3324.java:489)
        at knot//net.minecraft.class_3324.method_14570(class_3324.java:192)
        at knot//net.minecraft.class_11549$class_11551.method_72305(class_11549.java:198)
        at knot//net.minecraft.class_11549.method_72296(class_11549.java:91)
        at knot//net.minecraft.class_8610.method_52408(class_8610.java:178)
        at knot//net.minecraft.class_8736.method_53043(class_8736.java:22)
        at knot//net.minecraft.class_8736.method_65081(class_8736.java:8)
        at knot//net.minecraft.class_11980$class_11981.method_74450(class_11980.java:55)
        at knot//net.minecraft.class_11980.method_74449(class_11980.java:38)
        at knot//net.minecraft.server.MinecraftServer.method_76677(MinecraftServer.java:1047)
        at knot//net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:771)
        at knot//net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:301)
        at java.base/java.lang.Thread.run(Thread.java:1583)
A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
        Minecraft Version: 1.21.11
        Minecraft Version ID: 1.21.11
        Operating System: Linux (amd64) version 6.8.0-134-generic
        Java Version: 21.0.11, Ubuntu
        Java VM Version: OpenJDK 64-Bit Server VM (mixed mode, sharing), Ubuntu
        Memory: 1406950928 bytes (1341 MiB) / 2147483648 bytes (2048 MiB) up to 4294967296 bytes (4096 MiB)
        CPUs: 8
        Processor Vendor: AuthenticAMD
        Processor Name: AMD Ryzen 5 2400GE with Radeon Vega Graphics
        Identifier: AuthenticAMD Family 23 Model 17 Stepping 0
        Microarchitecture: Zen
        Frequency (GHz): 3.20
        Number of physical packages: 1
        Number of physical CPUs: 4
        Number of logical CPUs: 8
        Graphics card #0 name: Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series]
        Graphics card #0 vendor: Advanced Micro Devices, Inc. [AMD/ATI] (0x1002)
        Graphics card #0 VRAM (MiB): 258.00
        Graphics card #0 deviceId: 0x15dd
        Graphics card #0 versionInfo: unknown
        Virtual memory max (MiB): 11554.00
        Virtual memory used (MiB): 7920.32
        Swap memory total (MiB): 4096.00
        Swap memory used (MiB): 172.50
        Space in storage for jna.tmpdir (MiB): <path not set>
        Space in storage for org.lwjgl.system.SharedLibraryExtractPath (MiB): <path not set>
        Space in storage for io.netty.native.workdir (MiB): <path not set>
        Space in storage for java.io.tmpdir (MiB): available: 143834.69, total: 231082.81
        Space in storage for workdir (MiB): available: 143834.69, total: 231082.81
        JVM Flags: 2 total; -Xmx4G -Xms2G
        Debug Flags: 0 total;
        Fabric Mods:
                bluemap: BlueMap 5.16
                        com_flowpowered_flow-math: flow-math 1.0.3
                        de_bluecolored_bluenbt: bluenbt 3.5.0
                fabric-api: Fabric API 0.141.4+1.21.11
                        fabric-api-base: Fabric API Base 1.0.5+4ebb5c083e
                        fabric-api-lookup-api-v1: Fabric API Lookup API (v1) 1.6.114+20dc27073e
                        fabric-biome-api-v1: Fabric Biome API (v1) 17.1.1+4fc5413f3e
                        fabric-block-api-v1: Fabric Block API (v1) 1.1.10+4ebb5c083e
                        fabric-block-view-api-v2: Fabric BlockView API (v2) 1.0.39+4ebb5c083e
                        fabric-command-api-v2: Fabric Command API (v2) 2.4.7+6b42a6003e
                        fabric-content-registries-v0: Fabric Content Registries (v0) 10.2.14+4fc5413f3e
                        fabric-convention-tags-v1: Fabric Convention Tags 2.1.55+7f945d5b3e
                        fabric-convention-tags-v2: Fabric Convention Tags (v2) 2.17.3+8ef948ba3e
                        fabric-crash-report-info-v1: Fabric Crash Report Info (v1) 0.3.23+4ebb5c083e
                        fabric-data-attachment-api-v1: Fabric Data Attachment API (v1) 1.8.48+eed0806f3e
                        fabric-data-generation-api-v1: Fabric Data Generation API (v1) 23.4.1+69974c4e3e
                        fabric-dimensions-v1: Fabric Dimensions API (v1) 4.0.28+4fc5413f3e
                        fabric-entity-events-v1: Fabric Entity Events (v1) 3.1.1+1d0ab4303e
                        fabric-events-interaction-v0: Fabric Events Interaction (v0) 4.1.1+3b89ecf63e
                        fabric-game-rule-api-v1: Fabric Game Rule API (v1) 2.0.3+4fc5413f3e
                        fabric-item-api-v1: Fabric Item API (v1) 11.5.20+d0c46b9e3e
                        fabric-item-group-api-v1: Fabric Item Group API (v1) 4.2.36+4fc5413f3e
                        fabric-lifecycle-events-v1: Fabric Lifecycle Events (v1) 2.6.15+4ebb5c083e
                        fabric-loot-api-v2: Fabric Loot API (v2) 3.0.73+3f89f5a53e
                        fabric-loot-api-v3: Fabric Loot API (v3) 2.0.20+78c8b4663e
                        fabric-message-api-v1: Fabric Message API (v1) 6.1.12+4ebb5c083e
                        fabric-networking-api-v1: Fabric Networking API (v1) 5.1.6+6b6d71a53e
                        fabric-object-builder-api-v1: Fabric Object Builder API (v1) 21.1.40+4fc5413f3e
                        fabric-particles-v1: Fabric Particles (v1) 4.2.12+4fc5413f3e
                        fabric-recipe-api-v1: Fabric Recipe API (v1) 8.2.4+4ebb5c083e
                        fabric-registry-sync-v0: Fabric Registry Sync (v0) 6.2.6+1718722b3e
                        fabric-rendering-fluids-v1: Fabric Rendering Fluids (v1) 3.1.43+4ebb5c083e
                        fabric-resource-conditions-api-v1: Fabric Resource Conditions API (v1) 5.0.35+4fc5413f3e
                        fabric-resource-loader-v0: Fabric Resource Loader (v0) 3.3.4+4fc5413f3e
                        fabric-resource-loader-v1: Fabric Resource Loader (v1) 1.0.10+78c8b4663e
                        fabric-screen-handler-api-v1: Fabric Screen Handler API (v1) 1.3.162+4fc5413f3e
                        fabric-serialization-api-v1: Fabric Serialization API (v1) 1.0.5+4ebb5c083e
                        fabric-tag-api-v1: Fabric Tag API (v1) 1.2.20+4fc5413f3e
                        fabric-transfer-api-v1: Fabric Transfer API (v1) 6.0.25+4fc5413f3e
                        fabric-transitive-access-wideners-v1: Fabric Transitive Access Wideners (v1) 7.1.0+014c8cec3e
                fabricloader: Fabric Loader 0.19.3
                        mixinextras: MixinExtras 0.5.4
                farmersdelight: Farmer's Delight 1.21.11-3.4.9+refabricated
                        mm: Manningham Mills 2.3
                java: OpenJDK 64-Bit Server VM 21
                lithostitched: Lithostitched 1.7.2
                minecraft: Minecraft 1.21.11
                plan: Plan 5.7+build.3306
                terralith: Terralith 2.6.1
        Server Running: true
        Player Count: 0 / 4; []
        Active Data Packs: vanilla, fabric-convention-tags-v2, farmersdelight, lithostitched, terralith
        Available Data Packs: fabric-convention-tags-v2, farmersdelight, lithostitched, minecart_improvements, redstone_experiments, terralith, trade_rebalance, vanilla
        Enabled Feature Flags: minecraft:vanilla
        World Generation: Stable
        World Seed: -8411272779325425654
        Suppressed Exceptions: NONE
        Is Modded: Definitely; Server brand changed to 'fabric'
        Type: Dedicated Server (map_server.txt)
        Active Data Packs: vanilla, fabric-convention-tags-v2, farmersdelight, lithostitched, terralith
        Available Data Packs: fabric-convention-tags-v2, farmersdelight, lithostitched, minecart_improvements, redstone_experiments, terralith, trade_rebalance, vanilla
        Enabled Feature Flags: minecraft:vanilla
        World Generation: Stable
        World Seed: -8411272779325425654
        Suppressed Exceptions: NONE
        Is Modded: Definitely; Server brand changed to 'fabric'
        Type: Dedicated Server (map_server.txt)

Environment

• Minecraft: 1.21.11
• Fabric Loader: 0.19.3
• Fabric API: 0.141.4+1.21.11
• Plan: 5.7+build.3306
• Java: 21.0.11 (Ubuntu)
• OS: Linux (Ubuntu Server)

Related Issues

Found a recurring pattern across multiple prior issues (different MC versions: 1.20.1),
all involving class_2168 (ServerCommandSource) and Plan's Fabric command/mixin hooks failing:

1. Issue 3412 - NoSuchMethodError-style crash, resolved by maintainer noting
   "PlanFabric-5.6-dev-build-2703 only supports 1.20.4"

2. Issue 3441 - Identical KickCommandMixin injection failure
   (dev-build-2731), resolved by maintainer noting to use the 1.20.1-specific stable
   release instead of a dev build

Both cases indicate Plan's Fabric dev builds are extremely version-specific and
mismatches between the installed build and the exact target Minecraft version
reliably cause crashes involving ServerCommandSource (class_2168) hooks.

In our case, we used a build explicitly listed as supporting 1.21.11 (5.7 build 3306,
not a dev build), yet encountered the same class of error — suggesting this may not
be limited to dev builds, or that build 3306 has a similar internal version mismatch.

[AuroraLS3]

You need permission api as well.

[sebastianzehner]

You need permission api as well.

Thanks a lot for the quick help and installing fabric-permissions-api resolved the issue. Players can now join without the server crashing.

For what it's worth, I couldn't find this dependency mentioned anywhere in the documentation (neither on the Plan wiki nor on the Modrinth project page), so it might be worth adding a note there for other Fabric users running into the same crash.

Thanks again for the help!