VanillaBackport (and GravesX) No Longer Working past de44ca3

[autoteelar]

I have tried that...

• I am using the latest Arclight build

• I have read the FAQ and Troubleshooting, they didn't solve my issue

• I have searched existing Issues and found no duplicates

• The mods and/or plugins I use support my Minecraft version

• I have installed all required dependencies for the mods and/or plugins

• I have updated all mods and/or plugins to their latest versions

• This issue cannot be reproduced on a Spigot server
  (Mod-related issues are considered non-reproducible on Spigot)

• This issue cannot be reproduced on the Mod Loader server (Forge/NeoForge/Fabric)
  (Plugin-related issues are considered non-reproducible on mod loaders)

Minecraft Version

1.21.1

Arclight Version

1.0.2-SNAPSHOT-0769551

OS Version

Linux

Java Version

openjdk version "21.0.8" 2025-07-15
OpenJDK Runtime Environment (build 21.0.8+9-void-r1)
OpenJDK 64-Bit Server VM (build 21.0.8+9-void-r1, mixed mode, sharing)

Related Mods and/or Plugins (Name & Version)

mods:
Vanilla Backport
Arclight itself

Plugins that also notice didnt work on new version:
GravesX

Issue Description

everything was working fine on de44ca3. but now i can't update because its causing issues.

i also had issues with GravesX not working at all on newer versions, but so far i am stuck on de44ca3 and can not update.

Steps to Reproduce

1. download Arclight latest build

2. download vanilla backport from the development discord channel (or i can send you it) (or other plugins like GravesX that wasnt working grave would not show on death and /graves did nothing)

3. notice a difference of it not working compared to de44ca3 which everything works.

Server Logs

[16May2026 22:32:42.847] [main/INFO] [FabricLoader/GameProvider/]: Loading Minecraft 1.21.1 Arclight arclight-1.21.1-1.0.2-SNAPSHOT-0769551 with Fabric Loader 0.19.2
mainEx[16May2026 22:32:42.849] [main/INFO] [FabricLoader/GameRemap/]: Fabric is preparing JARs on first launch, this may take a few seconds...
mainEx[16May2026 22:32:42.883] [ForkJoinPool-2-worker-10/WARN] [FabricLoader/Metadata/]: Mod vanillabackport uses the version 1.2.26w16a which isn't compatible with Loader's extended semantic version format (Could not parse version number component '26w16a'!), SemVer is recommended for reliably evaluating dependencies and prioritizing newer version
ForkJoinPool-2-worker-10Ex[16May2026 22:32:42.891] [ForkJoinPool-2-worker-15/WARN] [FabricLoader/Metadata/]: The mod "accessories_compat_layer" contains invalid entries in its mod json:

• Unsupported root entry "#COMMENT_breaks" at line 53 column 20
  ForkJoinPool-2-worker-15Ex[16May2026 22:32:43.077] [main/WARN] [FabricLoader/Resolution/]: Warnings were found!

• Mod 'Custom Portals' (customportals) 3.6.2 recommends version 11.0.0 or later of modmenu, which is missing!

  • You should install version 11.0.0 or later of modmenu for the optimal experience.

• Mod 'Debugify' (debugify) 1.21.1+1.0 recommends any version of modmenu, which is missing!

  • You should install any version of modmenu for the optimal experience.

• Mod 'Forge Config API Port' (forgeconfigapiport) 21.1.6 recommends any version of modmenu, which is missing!

  • You should install any version of modmenu for the optimal experience.
    mainEx[16May2026 22:32:43.079] [main/INFO] [FabricLoader/]: Loading 164 mods:

  • accessories 1.1.0-beta.53+1.21.1

  • accessories_compat_layer 0.1.12
    -- mixinsquared 0.3.4

  • aether 1.5.11
    |-- cumulus_menus 2.0.7
    |-- mm_shedaniel 2.4.1
    -- nitrogen_internals 1.1.21

  • architectury 13.0.8

  • arclight 1.0.2-SNAPSHOT+0769551
    -- fabric-permissions-api-v0 0.3.1

  • bettersafebed 1.21-16

  • cloth-config 15.0.140
    -- cloth-basic-math 0.6.1

  • cog 2.1.1+1.21

  • collective 8.19

  • cuddling 1.0.0

  • customportals 3.6.2
    |-- cardinal-components-base 6.1.0
    -- cardinal-components-world 6.1.0

  • debugify 1.21.1+1.0

  • easyauth 3.0.25
    |-- at_favre_lib_bcrypt 0.10.2
    |-- at_favre_lib_bytes 1.6.1
    |-- com_mysql_mysql-connector-j 8.2.0
    |-- com_typesafe_config 1.4.3
    |-- de_mkammerer_argon2-jvm 2.11
    |-- de_mkammerer_argon2-jvm-nolibs 2.11
    |-- fabric-permissions-api-v0 0.3.1
    |-- io_leangen_geantyref_geantyref 1.3.13
    |-- net_java_dev_jna_jna 5.13.0
    |-- org_apache_commons_commons-text 1.10.0
    |-- org_iq80_leveldb_leveldb 0.12
    |-- org_iq80_leveldb_leveldb-api 0.12
    |-- org_mongodb_bson 4.11.1
    |-- org_mongodb_mongodb-driver-core 4.11.1
    |-- org_mongodb_mongodb-driver-sync 4.11.1
    |-- org_spongepowered_configurate-core 4.1.2
    |-- org_spongepowered_configurate-hocon 4.1.2
    -- server_translations_api 2.3.1+1.21-pre2
    -- packet_tweaker 0.5.1+24w03b

  • easywhitelist 1.1.0

  • eatbottle 1.0.1+mc1.21.1

  • emi 1.1.22+1.21.1+fabric

  • fabric-api 0.116.11+1.21.1
    |-- fabric-api-base 0.4.42+6573ed8c19
    |-- fabric-api-lookup-api-v1 1.6.72+7b3d111d19
    |-- fabric-biome-api-v1 13.0.31+d527f9fd19
    |-- fabric-block-api-v1 1.1.0+0bc3503219
    |-- fabric-block-view-api-v2 1.0.11+ebb2264e19
    |-- fabric-blockrenderlayer-v1 1.1.52+0af3f5a719
    |-- fabric-client-tags-api-v1 1.1.15+6573ed8c19
    |-- fabric-command-api-v1 1.2.49+f71b366f19
    |-- fabric-command-api-v2 2.2.28+6ced4dd919
    |-- fabric-commands-v0 0.2.66+df3654b319
    |-- fabric-content-registries-v0 8.0.19+b559734419
    |-- fabric-convention-tags-v1 2.1.7+7f945d5b19
    |-- fabric-convention-tags-v2 2.12.0+c3656daa19
    |-- fabric-crash-report-info-v1 0.2.29+0af3f5a719
    |-- fabric-data-attachment-api-v1 1.4.6+5b36e0f719
    |-- fabric-data-generation-api-v1 20.2.37+60a6976219
    |-- fabric-dimensions-v1 4.0.1+65213ef819
    |-- fabric-entity-events-v1 1.8.0+2b27e0a419
    |-- fabric-events-interaction-v0 0.7.13+ba9dae0619
    |-- fabric-game-rule-api-v1 1.0.53+6ced4dd919
    |-- fabric-item-api-v1 11.2.0+3b3cb2e819
    |-- fabric-item-group-api-v1 4.1.7+def88e3a19
    |-- fabric-key-binding-api-v1 1.0.47+0af3f5a719
    |-- fabric-keybindings-v0 0.2.45+df3654b319
    |-- fabric-lifecycle-events-v1 2.6.0+0865547519
    |-- fabric-loot-api-v2 3.0.15+3f89f5a519
    |-- fabric-loot-api-v3 1.0.3+3f89f5a519
    |-- fabric-message-api-v1 6.0.14+8aaf3aca19
    |-- fabric-model-loading-api-v1 2.1.0+b4d813fc19
    |-- fabric-networking-api-v1 4.3.0+c7469b2119
    |-- fabric-object-builder-api-v1 15.2.1+40875a9319
    |-- fabric-particles-v1 4.0.2+6573ed8c19
    |-- fabric-recipe-api-v1 5.0.15+2475392c19
    |-- fabric-registry-sync-v0 5.3.1+e3eddc2119
    |-- fabric-renderer-api-v1 3.4.1+b4d813fc19
    |-- fabric-renderer-indigo 1.7.1+c705a49c19
    |-- fabric-renderer-registries-v1 3.2.69+df3654b319
    |-- fabric-rendering-data-attachment-v1 0.3.49+73761d2e19
    |-- fabric-rendering-fluids-v1 3.1.6+1daea21519
    |-- fabric-rendering-v0 1.1.72+df3654b319
    |-- fabric-rendering-v1 5.1.0+ab4c25a019
    |-- fabric-resource-conditions-api-v1 4.3.0+8dc279b119
    |-- fabric-resource-loader-v0 1.3.1+5b5275af19
    |-- fabric-screen-api-v1 2.0.25+8b68f1c719
    |-- fabric-screen-handler-api-v1 1.3.90+b559734419
    |-- fabric-sound-api-v1 1.0.23+6573ed8c19
    |-- fabric-transfer-api-v1 5.4.4+7b3d111d19
    -- fabric-transitive-access-wideners-v1 6.2.0+45b9699719

  • fabric-language-kotlin 1.13.10+kotlin.2.3.20
    |-- org_jetbrains_kotlin_kotlin-reflect 2.3.20
    |-- org_jetbrains_kotlin_kotlin-stdlib 2.3.20
    |-- org_jetbrains_kotlin_kotlin-stdlib-jdk7 2.3.20
    |-- org_jetbrains_kotlin_kotlin-stdlib-jdk8 2.3.20
    |-- org_jetbrains_kotlinx_atomicfu-jvm 0.32.1
    |-- org_jetbrains_kotlinx_kotlinx-coroutines-core-jvm 1.10.2
    |-- org_jetbrains_kotlinx_kotlinx-coroutines-jdk8 1.10.2
    |-- org_jetbrains_kotlinx_kotlinx-datetime-jvm 0.7.1
    |-- org_jetbrains_kotlinx_kotlinx-io-bytestring-jvm 0.9.0
    |-- org_jetbrains_kotlinx_kotlinx-io-core-jvm 0.9.0
    |-- org_jetbrains_kotlinx_kotlinx-serialization-cbor-jvm 1.10.0
    |-- org_jetbrains_kotlinx_kotlinx-serialization-core-jvm 1.10.0
    -- org_jetbrains_kotlinx_kotlinx-serialization-json-jvm 1.10.0

  • fabricloader 0.19.2
    -- mixinextras 0.5.4

  • forgeconfigapiport 21.1.6
    |-- com_electronwill_night-config_core 3.8.0
    -- com_electronwill_night-config_toml 3.8.0

  • frost 2.1.1

  • immersive_aircraft 1.4.3+1.21.1
    -- org_mariuszgromada_math_mathparser_org-mxparser 5.2.1

  • immersive_portals 6.0.6
    -- dimlib 1.1.0+mc1.21.1
    -- midnightlib 1.5.7

  • immersivelanterns 1.0.6

  • java 21

  • luckperms 5.4.140
    -- fabric-permissions-api-v0 0.3.1

  • minecraft 1.21.1

  • moderner_beta 4.1.2+1.21.1

  • monkeylib538 2.0.2
    -- monkeylib538-common 2.0.2
    -- blue_endless_jankson 1.2.3

  • more_slabs_stairs_and_walls 4.2.0

  • no_teleport_cooldown 1.0.10

  • nochatreports 1.21.1-v2.9.1

  • nocreeperexplode 1.0.0

  • nostalgic_tweaks 2.0.0-beta.922

  • nyfsquiver 2.0.3
    -- commonnetworking 1.0.11-1.21

  • openpartiesandclaims 0.26.1

  • owo 0.12.15.4+1.21
    |-- io_wispforest_endec 0.1.5.1
    |-- io_wispforest_endec_gson 0.1.3.1
    |-- io_wispforest_endec_jankson 0.1.3.1
    -- io_wispforest_endec_netty 0.1.2

  • platform 1.3

  • playerplates 21.1.0+mc1.21.1

  • recallpotion 1.0.0

  • skinrestorer 2.7.0+1.21-fabric
    -- org_mineskin_java-client 3.2.1-SNAPSHOT

  • sophisticatedbackpacks 1.21.1-3.23.4.3.106

  • sophisticatedcore 1.21.1-1.2.9.21.168
    |-- porting_lib_conditions 3.1.0-beta.47+1.21.1
    |-- porting_lib_core 3.1.0-beta.47+1.21.1
    |-- porting_lib_fluids 3.1.0-beta.47+1.21.1
    |-- porting_lib_item_abilities 3.1.0-beta.47+1.21.1
    |-- porting_lib_lazy_registration 3.1.0-beta.47+1.21.1
    |-- porting_lib_level_events 3.1.0-beta.47+1.21.1
    |-- porting_lib_loot 3.1.0-beta.47+1.21.1
    |-- porting_lib_model_loader 3.1.0-beta.47+1.21.1
    |-- porting_lib_render_types 3.1.0-beta.47+1.21.1
    |-- porting_lib_transfer 3.1.0-beta.47+1.21.1
    -- team_reborn_energy 4.1.0

  • sophisticatedstorage 1.21.1-1.3.7.9.139

  • sophisticatedstorageinmotion 1.21.1-0.10.5.1.38

  • stackablepotions 1.0.0

  • toms_storage 2.3.0
    |-- cardinal-components-base 6.1.0
    -- cardinal-components-block 6.1.0

  • toms_trading_network 0.3.0

  • trinkets 3.10.0
    |-- cardinal-components-base 6.1.0
    -- cardinal-components-entity 6.1.0

  • txnilib 1.0.24

  • vanillabackport 1.2.26w16a

  • xaerominimap 25.3.10
    -- xaerolib 1.1.0

  • xaeroworldmap 1.40.11
    -- xaerolib 1.1.0

  • yet_another_config_lib_v3 3.8.2+1.21.1-fabric
    |-- com_twelvemonkeys_common_common-image 3.12.0
    |-- com_twelvemonkeys_common_common-io 3.12.0
    |-- com_twelvemonkeys_common_common-lang 3.12.0
    |-- com_twelvemonkeys_imageio_imageio-core 3.12.0
    |-- com_twelvemonkeys_imageio_imageio-metadata 3.12.0
    |-- com_twelvemonkeys_imageio_imageio-webp 3.12.0
    |-- org_quiltmc_parsers_gson 0.2.1
    -- org_quiltmc_parsers_json 0.2.1
    mainEx[16May2026 22:32:43.261] [main/INFO] [FabricLoader/Mixin/]: SpongePowered MIXIN Subsystem Version=0.8.7 Source=file:/home/ichigo/Documents/testmcserv/libraries/net/fabricmc/sponge-mixin/0.17.2+mixin.0.8.7/sponge-mixin-0.17.2+mixin.0.8.7.jar Service=Knot/Fabric Env=SERVER
    mainEx[16May2026 22:32:43.303] [main/INFO] [FabricLoader/Mixin/]: Compatibility level set to JAVA_17
    mainEx[16May2026 22:32:43.308] [main/INFO] [FabricLoader/Mixin/]: Compatibility level set to JAVA_21
    mainEx[16May2026 22:32:43.669] [main/INFO] [Arclight/]: Using locale en_us and fallback locale en_us
    mainEx[16May2026 22:32:43.673] [main/INFO] [Arclight/]:

    ___ ___ __ /
    / | ______/ (_) / / / /
    / /| |/ / / / / _ / _ //
    / ___ / / / // / / / / // / /
    // |// _///_ //// /
    // /

  Version 诸王 (Feudal Kings) / arclight-fabric-1.21.1-1.0.2-SNAPSHOT+0769551
  Build Date 2026-05-09 08:48:42

mainEx[16May2026 22:32:43.739] [main/WARN] [FabricLoader/Mixin/]: Reference map 'forgeconfigapiport.common.refmap.json' for forgeconfigapiport.common.mixins.json could not be read. If this is a development environment you can ignore this message
mainEx[16May2026 22:32:43.802] [main/INFO] [MM-shedaniel/]: Started MM (shedaniel's fork) at me/shedaniel/gen/mixin/
mainEx[16May2026 22:32:43.815] [main/WARN] [FabricLoader/Mixin/]: Reference map 'Manningham Mills-refmap.json' for mixins.mm_shedaniel.json could not be read. If this is a development environment you can ignore this message
mainEx[16May2026 22:32:43.818] [main/WARN] [FabricLoader/Mixin/]: Reference map 'moderner_beta.refmap.json' for moderner_beta-common.mixins.json could not be read. If this is a development environment you can ignore this message
mainEx[16May2026 22:32:43.859] [main/WARN] [FabricLoader/Mixin/]: Reference map 'yet_another_config_lib_v3.refmap.json' for yacl.mixins.json could not be read. If this is a development environment you can ignore this message
mainEx[16May2026 22:32:43.859] [main/WARN] [FabricLoader/Mixin/]: Reference map 'yet_another_config_lib_v3.refmap.json' for yacl-fabric.mixins.json could not be read. If this is a development environment you can ignore this message
mainEx[16May2026 22:32:43.897] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_906 (java.lang.ClassNotFoundException: net/minecraft/class_906)
mainEx[16May2026 22:32:43.898] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_906 was not found porting_lib_item_abilities.mixins.json:FishingHookRendererMixin from mod porting_lib_item_abilities
mainEx[16May2026 22:32:44.038] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_310 (java.lang.ClassNotFoundException: net/minecraft/class_310)
mainEx[16May2026 22:32:44.038] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_310 was not found aether.mixins.json:client.accessor.MinecraftAccessor from mod aether
mainEx[16May2026 22:32:44.822] [main/WARN] [FabricLoader/Mixin/]: Error loading class: com/electronwill/nightconfig/core/io/IoUtils (java.lang.ClassNotFoundException: com/electronwill/nightconfig/core/io/IoUtils)
mainEx[16May2026 22:32:44.850] [main/WARN] [FabricLoader/Mixin/]: Error loading class: dev/onyxstudios/cca/api/v3/component/ComponentKey (java.lang.ClassNotFoundException: dev/onyxstudios/cca/api/v3/component/ComponentKey)
mainEx[16May2026 22:32:44.896] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_287 (java.lang.ClassNotFoundException: net/minecraft/class_287)
mainEx[16May2026 22:32:44.896] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_287 was not found owo.mixins.json:BufferBuilderAccessor from mod owo
mainEx[16May2026 22:32:44.898] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_437 (java.lang.ClassNotFoundException: net/minecraft/class_437)
mainEx[16May2026 22:32:44.898] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_437 was not found owo.mixins.json:ScreenAccessor from mod owo
mainEx[16May2026 22:32:44.912] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_638 (java.lang.ClassNotFoundException: net/minecraft/class_638)
mainEx[16May2026 22:32:44.912] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_638 was not found porting_lib_level_events.mixins.json:client.ClientLevelMixin from mod porting_lib_level_events
mainEx[16May2026 22:32:44.937] [main/WARN] [FabricLoader/Mixin/]: Error loading class: jeresources/api/util/BiomeHelper (java.lang.ClassNotFoundException: jeresources/api/util/BiomeHelper)
mainEx[16May2026 22:32:44.938] [main/WARN] [FabricLoader/Mixin/]: Error loading class: yalter/mousetweaks/Main (java.lang.ClassNotFoundException: yalter/mousetweaks/Main)
mainEx[16May2026 22:32:44.938] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_572$class_573 (java.lang.ClassNotFoundException: net/minecraft/class_572$class_573)
mainEx[16May2026 22:32:44.938] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_572$class_573 was not found vanillabackport.mixins.json:enums.HumanoidArmPoseMixin from mod vanillabackport
mainEx[16May2026 22:32:45.120] [main/WARN] [FabricLoader/Mixin/]: Error loading class: net/minecraft/class_314 (java.lang.ClassNotFoundException: net/minecraft/class_314)
mainEx[16May2026 22:32:45.120] [main/WARN] [FabricLoader/Mixin/]: @mixin target net.minecraft.class_314 was not found mixins.mm_shedaniel.json:net.minecraft.class_314 from mod mm_shedaniel
mainEx[16May2026 22:32:45.216] [main/INFO] [FabricLoader/MixinExtras|Service/]: Initializing MixinExtras via com.llamalad7.mixinextras.service.MixinExtrasServiceImpl(version=0.5.4).
mainEx[16May2026 22:32:50.420] [main/ERROR] [FabricLoader/]: Minecraft has crashed!
mainEx net.fabricmc.loader.impl.FormattedException: java.lang.BootstrapMethodError: java.lang.RuntimeException: Mixin transformation of net.minecraft.class_1681 failed
at net.fabricmc.loader.impl.FormattedException.ofLocalized(FormattedException.java:63) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:516) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:72) [fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotServer.main(KnotServer.java:23) [fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.server.FabricServerLauncher.main(FabricServerLauncher.java:69) [fabric-loader-0.19.2.jar:?]
at io.izzel.arclight.boot.fabric.application.Main_Fabric.main(Main_Fabric.java:33) [arclight.jar:arclight-1.21.1-1.0.2-SNAPSHOT-0769551]
at io.izzel.arclight.server.Launcher.main(Launcher.java:39) [arclight.jar:arclight-1.21.1-1.0.2-SNAPSHOT-0769551]
Caused by: java.lang.BootstrapMethodError: java.lang.RuntimeException: Mixin transformation of net.minecraft.class_1681 failed
at knot/net.minecraft.class_1299.(EntityTypeMixin.java:214) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1802.(class_1802.java:854) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_6089.method_9530(class_6089.java:64) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26172(BlockBehaviour_BlockStateBaseMixin.java:1058) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26218(BlockBehaviour_BlockStateBaseMixin.java:1054) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970.method_9549(BlockBehaviourMixin.java:355) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971$class_3752.(class_4970.java:1341) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26200(BlockBehaviour_BlockStateBaseMixin.java:869) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2246.(class_2246.java:1259) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2358.method_10199(FireBlockMixin_Fabric.java:336) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2966.method_12851(BootstrapMixin.java:52) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.Main.main(Main.java:108) ~[server-intermediary.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:514) ~[fabric-loader-0.19.2.jar:?]
... 5 more
Caused by: java.lang.RuntimeException: Mixin transformation of net.minecraft.class_1681 failed
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:440) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:336) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:231) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.19.2.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at knot/net.minecraft.class_1299.(EntityTypeMixin.java:214) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1802.(class_1802.java:854) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_6089.method_9530(class_6089.java:64) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26172(BlockBehaviour_BlockStateBaseMixin.java:1058) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26218(BlockBehaviour_BlockStateBaseMixin.java:1054) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970.method_9549(BlockBehaviourMixin.java:355) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971$class_3752.(class_4970.java:1341) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26200(BlockBehaviour_BlockStateBaseMixin.java:869) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2246.(class_2246.java:1259) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2358.method_10199(FireBlockMixin_Fabric.java:336) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2966.method_12851(BootstrapMixin.java:52) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.Main.main(Main.java:108) ~[server-intermediary.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:514) ~[fabric-loader-0.19.2.jar:?]
... 5 more
Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:380) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:237) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:435) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:336) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:231) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.19.2.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at knot/net.minecraft.class_1299.(EntityTypeMixin.java:214) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1802.(class_1802.java:854) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_6089.method_9530(class_6089.java:64) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26172(BlockBehaviour_BlockStateBaseMixin.java:1058) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26218(BlockBehaviour_BlockStateBaseMixin.java:1054) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970.method_9549(BlockBehaviourMixin.java:355) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971$class_3752.(class_4970.java:1341) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26200(BlockBehaviour_BlockStateBaseMixin.java:869) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2246.(class_2246.java:1259) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2358.method_10199(FireBlockMixin_Fabric.java:336) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2966.method_12851(BootstrapMixin.java:52) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.Main.main(Main.java:108) ~[server-intermediary.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:514) ~[fabric-loader-0.19.2.jar:?]
... 5 more
Caused by: org.spongepowered.asm.mixin.injection.throwables.InjectionError: Critical injection failure: Callback method setChickenVariant(Lnet/minecraft/class_239;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;Lnet/minecraft/class_1428;)V in vanillabackport.mixins.json:common.entities.projectile.ThrownEggMixin from mod vanillabackport failed injection check, (0/1) succeeded. Scanned 0 target(s). No refMap loaded.
at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.postInject(InjectionInfo.java:531) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at knot/com.llamalad7.mixinextras.wrapper.InjectorWrapperImpl.doPostInject(InjectorWrapperImpl.java:88) ~[mixinextras-0.5.4-edfcdd3df0b35281.jar:?]
at knot/com.llamalad7.mixinextras.sugar.impl.SugarWrapperImpl.doPostInject(SugarWrapperImpl.java:88) ~[mixinextras-0.5.4-edfcdd3df0b35281.jar:?]
at knot/com.llamalad7.mixinextras.wrapper.WrapperInjectionInfo.postInject(WrapperInjectionInfo.java:85) ~[mixinextras-0.5.4-edfcdd3df0b35281.jar:?]
at org.spongepowered.asm.mixin.transformer.MixinTargetContext.applyInjections(MixinTargetContext.java:1477) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyInjections(MixinApplicatorStandard.java:832) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.lambda$runApplicatorPass$7(MixinApplicatorStandard.java:362) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.processMixins(MixinApplicatorStandard.java:381) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.runApplicatorPass(MixinApplicatorStandard.java:360) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:240) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.apply(TargetClassContext.java:437) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:418) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:351) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:237) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202) ~[sponge-mixin-0.17.2+mixin.0.8.7.jar:0.17.2+mixin.0.8.7]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:435) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:336) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:231) ~[fabric-loader-0.19.2.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.19.2.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at knot/net.minecraft.class_1299.(EntityTypeMixin.java:214) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_1802.(class_1802.java:854) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_6089.method_9530(class_6089.java:64) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26172(BlockBehaviour_BlockStateBaseMixin.java:1058) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26218(BlockBehaviour_BlockStateBaseMixin.java:1054) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970.method_9549(BlockBehaviourMixin.java:355) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971$class_3752.(class_4970.java:1341) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_4970$class_4971.method_26200(BlockBehaviour_BlockStateBaseMixin.java:869) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2246.(class_2246.java:1259) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2358.method_10199(FireBlockMixin_Fabric.java:336) ~[server-intermediary.jar:?]
at knot/net.minecraft.class_2966.method_12851(BootstrapMixin.java:52) ~[server-intermediary.jar:?]
at knot/net.minecraft.server.Main.main(Main.java:108) ~[server-intermediary.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:514) ~[fabric-loader-0.19.2.jar:?]
... 5 more
bash-5.3$

The Server Pack for Reproduce

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[autoteelar]

also mentioned here, apparently affects forge on 1.20.1 ItsBlackGear/VanillaBackport#314