fabric crashes when entering multiplayer

[Joshua Basulto]

---- Minecraft Crash Report ----
// My bad.

Time: 2024-07-17 11:17:18
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
    at com.google.common.collect.Iterators$6.transform(Iterators.java:829)
    at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:52)
    at net.minecraft.class_2370.remap(class_2370.java:744)
    at net.minecraft.class_2370.unmap(class_2370.java:875)
    at net.fabricmc.fabric.impl.registry.sync.RegistrySyncManager.unmap(RegistrySyncManager.java:368)
    at net.minecraft.class_310.handler$bma000$fabric-registry-sync-v0$disconnectAfter(class_310.java:11691)
    at net.minecraft.class_310.method_18096(class_310.java:2269)
    at net.minecraft.class_8673.method_10839(class_8673.java:319)
    at net.minecraft.class_2535.method_10768(class_2535.java:673)
    at net.minecraft.class_636.method_2927(class_636.java:290)
    at net.minecraft.class_310.method_1574(class_310.java:1908)
    at net.minecraft.class_310.method_1523(class_310.java:1246)
    at net.minecraft.class_310.method_1514(class_310.java:882)
    at net.minecraft.client.main.Main.main(Main.java:256)
    at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:470)
    at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74)
    at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Render thread
Stacktrace:
    at com.google.common.collect.Iterators$6.transform(Iterators.java:829)
    at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:52)
    at net.minecraft.class_2370.remap(class_2370.java:744)
    at net.minecraft.class_2370.unmap(class_2370.java:875)
    at net.fabricmc.fabric.impl.registry.sync.RegistrySyncManager.unmap(RegistrySyncManager.java:368)
    at net.minecraft.class_310.handler$bma000$fabric-registry-sync-v0$disconnectAfter(class_310.java:11691)
    at net.minecraft.class_310.method_18096(class_310.java:2269)
    at net.minecraft.class_8673.method_10839(class_8673.java:319)
    at net.minecraft.class_2535.method_10768(class_2535.java:673)
    at net.minecraft.class_636.method_2927(class_636.java:290)

-- Uptime --
Details:
    JVM uptime: 111.259s
    Wall uptime: 70.335s
    High-res time: 44.634s
    Client ticks: 508 ticks / 25.400s
Stacktrace:
    at net.minecraft.class_310.method_1587(class_310.java:2501)
    at net.minecraft.class_310.method_54580(class_310.java:949)
    at net.minecraft.class_310.method_1514(class_310.java:905)
    at net.minecraft.client.main.Main.main(Main.java:256)
    at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:470)
    at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74)
    at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)

-- Last reload --
Details:
    Reload number: 1
    Reload reason: initial
    Finished: Yes
    Packs: vanilla, fabric, accessories, advanced-xray-fabric, appleskin, armoroftheages, auditory, balm-fabric, beautify, betterf3, betterthirdperson, biolith, bobby, bosses_of_mass_destruction, caffeineconfig, cardinal-components, cardinal-components-base, cardinal-components-block, cardinal-components-chunk, cardinal-components-entity, cardinal-components-item, cardinal-components-level, cardinal-components-scoreboard, cardinal-components-world, carryon, chipped, chunky, cinderscapes, cinderscapes-client, cinderscapes-common, cinderscapes-worldgen, cloth-config, comforts, conditional-mixin, cool_elytra, cratedelight, creativecore, creeperoverhaul, cristellib, croptopia, dramaticdoors, duckling, eatinganimationid, elytratrims, entity_texture_features, epherolib, explorerscompass, fabric-api, fabric-api-base, fabric-api-lookup-api-v1, fabric-biome-api-v1, fabric-block-api-v1, fabric-block-view-api-v2, fabric-blockrenderlayer-v1, fabric-client-tags-api-v1, fabric-command-api-v1, fabric-command-api-v2, fabric-commands-v0, fabric-content-registries-v0, fabric-convention-tags-v1, fabric-convention-tags-v2, fabric-crash-report-info-v1, fabric-data-attachment-api-v1, fabric-data-generation-api-v1, fabric-dimensions-v1, fabric-entity-events-v1, fabric-events-interaction-v0, fabric-game-rule-api-v1, fabric-item-api-v1, fabric-item-group-api-v1, fabric-key-binding-api-v1, fabric-keybindings-v0, fabric-language-kotlin, fabric-lifecycle-events-v1, fabric-loot-api-v2, fabric-loot-api-v3, fabric-message-api-v1, fabric-model-loading-api-v1, fabric-networking-api-v1, fabric-object-builder-api-v1, fabric-particles-v1, fabric-recipe-api-v1, fabric-registry-sync-v0, fabric-renderer-api-v1, fabric-renderer-indigo, fabric-renderer-registries-v1, fabric-rendering-data-attachment-v1, fabric-rendering-fluids-v1, fabric-rendering-v0, fabric-rendering-v1, fabric-resource-conditions-api-v1, fabric-resource-loader-v0, fabric-screen-api-v1, fabric-screen-handler-api-v1, fabric-sound-api-v1, fabric-transfer-api-v1, fabric-transitive-access-wideners-v1, fabricloader, forf, freecam, friendsandfoes, geocluster, glassential, glore, grassoverhaul, horizontal_glass_panes, infinity-cave, iris, jade, jamlib, jankson, libgui, mavapi, mavm, medieval_buildings, mes, midnightlib, mns, more_armor_trims, mostructures, mr_dungeons_andtavernsdeserttempleoverhaul, mr_dungeons_andtavernsendcastlestandalone, mr_dungeons_andtavernsjungletempleoverhaul, mr_dungeons_andtavernsnetherfortressoverhaul, mr_dungeons_andtavernsoceanmonumentoverhaul, mr_dungeons_andtavernswoodlandmansionoverhaul, mss, mvs, natures_spirit, necronomicon, new_slab_variants, nicer-skies, noisium, notenoughanimations, polymer-core, polymer-resource-pack, resourcefulconfig, simple_backpack, sodium, sodium-extra, sound_physics_remastered, spectrelib, status-effect-bars, stendhal, sulfurpotassiummod, terraform-biome-remapper-api-v1, terraform-shapes-api-v1, terraform-surfaces-api-v1, terraform-wood-api-v1, the_bumblezone, time_on_display, toggleableitemframes, toomanypaintings, travelersbackpack, trimeffects, universal-graves, utility_belt, variantbarrels, variantbeehives, variantbookshelves, variantcomposters, variantsandventures, visuality, waterframes, waxablecoral, waystones, xaerominimap, xaeroworldmap, yet_another_config_lib_v3, zoomify, minecraft:supporteatinganimation, file/Stay_True_1.21.zip, file/Better Cats v2.0 1.21.zip, file/Better Horses v2.0 1.21.zip, file/Torrezx-Bad_omen.zip, file/Torrezx-Sculk_power.zip, file/Torrezx-Warden_Power.zip, file/Torrezx-Heavy_core_tools.zip, file/waystones_1.21.zip
 

[Ugdhar]

These forums are for Minecraft Forge, not Fabric.

You would probably be better served posting this question wherever fabric support is given, most likely their discord server.