I tried only better advanced mods with neoforge 1.21.4 (21.4.43)
crash-2024-12-30_16.14.16-fml.txt
and it cant launch the game.
In the file is issue report.
Thanks for fixing it. Really want to play with this mod :)

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 2024-12-30 16:14:16
Description: Mod loading failures have occurred; consult the issue messages for more details

net.neoforged.neoforge.logging.CrashReportExtender$ModLoadingCrashException: Mod loading has failed

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

-- Head --
Thread: Render thread
Stacktrace:
at TRANSFORMER/[email protected]/betteradvancements.common.gui.BetterAdvancementTabType.(BetterAdvancementTabType.java:12) ~[?:?] {re:classloading}
-- Mod loading issue for: betteradvancements --
Details:
Mod file: /C:/Users/sfsla/curseforge/minecraft/Instances/MODS/mods/BetterAdvancements-NeoForge-1.21.4-0.4.4.24.jar
Failure message: Better Advancements (betteradvancements) encountered an error while dispatching the net.neoforged.fml.event.config.ModConfigEvent$Loading event
java.lang.IllegalAccessError: failed to access class net.minecraft.client.gui.screens.advancements.AdvancementTabType from class betteradvancements.common.gui.BetterAdvancementTabType (net.minecraft.client.gui.screens.advancements.AdvancementTabType is in module [email protected] of loader 'TRANSFORMER' @a6c54c3; betteradvancements.common.gui.BetterAdvancementTabType is in module [email protected] of loader 'TRANSFORMER' @a6c54c3)
Mod version: 0.4.4.24
Mod issues URL: https://github.com/way2muchnoise/BetterAdvancements/issues
Exception message: java.lang.IllegalAccessError: failed to access class net.minecraft.client.gui.screens.advancements.AdvancementTabType from class betteradvancements.common.gui.BetterAdvancementTabType (net.minecraft.client.gui.screens.advancements.AdvancementTabType is in module [email protected] of loader 'TRANSFORMER' @a6c54c3; betteradvancements.common.gui.BetterAdvancementTabType is in module [email protected] of loader 'TRANSFORMER' @a6c54c3)
Stacktrace:
at TRANSFORMER/[email protected]/betteradvancements.common.gui.BetterAdvancementTabType.(BetterAdvancementTabType.java:12) ~[BetterAdvancements-NeoForge-1.21.4-0.4.4.24.jar%23248!/:?] {re:classloading}
at TRANSFORMER/[email protected]/betteradvancements.neoforge.config.ConfigValues.pushChanges(ConfigValues.java:83) ~[BetterAdvancements-NeoForge-1.21.4-0.4.4.24.jar%23248!/:?] {re:classloading}
at TRANSFORMER/[email protected]/betteradvancements.neoforge.config.Config.onLoad(Config.java:22) ~[BetterAdvancements-NeoForge-1.21.4-0.4.4.24.jar%23248!/:?] {re:classloading}
at MC-BOOTSTRAP/net.neoforged.bus/net.neoforged.bus.EventBus.post(EventBus.java:350) ~[bus-8.0.2.jar%23123!/:?] {}
at MC-BOOTSTRAP/net.neoforged.bus/net.neoforged.bus.EventBus.post(EventBus.java:315) ~[bus-8.0.2.jar%23123!/:?] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.ModContainer.acceptEvent(ModContainer.java:158) ~[loader-6.0.4.jar%23120!/:6.0] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ModConfig.setConfig(ModConfig.java:79) ~[loader-6.0.4.jar%23120!/:6.0] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ConfigTracker.loadConfig(ConfigTracker.java:197) ~[loader-6.0.4.jar%23120!/:6.0] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ConfigTracker.openConfig(ConfigTracker.java:140) ~[loader-6.0.4.jar%23120!/:6.0] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ConfigTracker.lambda$loadConfigs$2(ConfigTracker.java:124) ~[loader-6.0.4.jar%23120!/:6.0] {}
at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[?:?] {re:computing_frames,re:mixin}
at java.base/java.util.Collections$SynchronizedCollection.forEach(Collections.java:2351) ~[?:?] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ConfigTracker.loadConfigs(ConfigTracker.java:124) ~[loader-6.0.4.jar%23120!/:6.0] {}
at MC-BOOTSTRAP/[email protected]/net.neoforged.fml.config.ConfigTracker.loadConfigs(ConfigTracker.java:119) ~[loader-6.0.4.jar%23120!/:6.0] {}
at TRANSFORMER/[email protected]/net.neoforged.neoforge.internal.CommonModLoader.lambda$begin$1(CommonModLoader.java:62) ~[neoforge-21.4.43-beta-universal.jar%23244!/:?] {re:classloading}
at java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1804) ~[?:?] {}
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?] {}
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?] {}
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?] {}

-- System Details --
Details:
Minecraft Version: 1.21.4
Minecraft Version ID: 1.21.4
Operating System: Windows 11 (amd64) version 10.0
Java Version: 21.0.3, Microsoft
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Microsoft
Memory: 296497712 bytes (282 MiB) / 708837376 bytes (676 MiB) up to 8589934592 bytes (8192 MiB)
CPUs: 10
Processor Vendor: GenuineIntel
Processor Name: 12th Gen Intel(R) Core(TM) i7-12700KF
Identifier: Intel64 Family 6 Model 151 Stepping 2
Microarchitecture: Alder Lake
Frequency (GHz): 3.61
Number of physical packages: 1
Number of physical CPUs: 5
Number of logical CPUs: 10
Graphics card #0 name: NVIDIA GeForce RTX 4070 SUPER
Graphics card #0 vendor: NVIDIA
Graphics card #0 VRAM (MiB): 12282.00
Graphics card #0 deviceId: VideoController1
Graphics card #0 versionInfo: 32.0.15.6636
Memory slot #0 capacity (MiB): 16384.00
Memory slot #0 clockSpeed (GHz): 3.20
Memory slot #0 type: DDR4
Memory slot #1 capacity (MiB): 16384.00
Memory slot #1 clockSpeed (GHz): 3.20
Memory slot #1 type: DDR4
Virtual memory max (MiB): 34605.42
Virtual memory used (MiB): 15513.98
Swap memory total (MiB): 2048.00
Swap memory used (MiB): 46.50
Space in storage for jna.tmpdir (MiB): available: 588306.69, total: 975917.00
Space in storage for org.lwjgl.system.SharedLibraryExtractPath (MiB): available: 588306.69, total: 975917.00
Space in storage for io.netty.native.workdir (MiB): available: 588306.69, total: 975917.00
Space in storage for java.io.tmpdir (MiB): available: 588306.69, total: 975917.00
Space in storage for workdir (MiB): available: 588306.69, total: 975917.00
JVM Flags: 4 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx8192m -Xms256m
ModLauncher: 11.0.4+main.d2e20e43
ModLauncher launch target: neoforgeclient
ModLauncher services:
sponge-mixin-0.15.2+mixin.0.8.7.jar mixin PLUGINSERVICE
loader-6.0.4.jar slf4jfixer PLUGINSERVICE
loader-6.0.4.jar runtime_enum_extender PLUGINSERVICE
at-modlauncher-11.0.1.jar accesstransformer PLUGINSERVICE
loader-6.0.4.jar runtimedistcleaner PLUGINSERVICE
modlauncher-11.0.4.jar mixin TRANSFORMATIONSERVICE
modlauncher-11.0.4.jar fml TRANSFORMATIONSERVICE
FML Language Providers:
[email protected]
[email protected]
[email protected]
[email protected]
Mod List:
appleskin-neoforge-mc1.21.3-3.0.6.jar |AppleSkin |appleskin |3.0.6+mc1.21.3 |Manifest: NOSIGNATURE
architectury-15.0.1-neoforge.jar |Architectury |architectury |15.0.1 |Manifest: NOSIGNATURE
balm-neoforge-1.21.4-21.4.5.jar |Balm |balm |21.4.5 |Manifest: NOSIGNATURE
BetterAdvancements-NeoForge-1.21.4-0.4.4.24.jar |Better Advancements |betteradvancements |0.4.4.24 |Manifest: NOSIGNATURE
cloth-config-17.0.144-neoforge.jar |Cloth Config v17 API |cloth_config |17.0.144 |Manifest: NOSIGNATURE
collective-1.21.4-7.89.jar |Collective |collective |7.89 |Manifest: NOSIGNATURE
corpse-neoforge-1.21.4-1.1.4.jar |Corpse |corpse |1.21.4-1.1.4 |Manifest: NOSIGNATURE
craftingtweaks-neoforge-1.21.4-21.4.2.jar |Crafting Tweaks |craftingtweaks |21.4.2 |Manifest: NOSIGNATURE
DnT-swamp-hut-overhaul-v2.1 [NeoForge].jar |Dungeons and Taverns Swamp Hut|mr_dungeons_andtavernsswamphut|1-v2.1 |Manifest: NOSIGNATURE
durabilitytooltip-1.1.5-neoforge-mc1.21.jar |Durability Tooltip |durabilitytooltip |1.1.5 |Manifest: NOSIGNATURE
easy-piglins-neoforge-1.21.4-1.0.13.jar |Easy Piglins |easy_piglins |1.21.4-1.0.13 |Manifest: NOSIGNATURE
easy-villagers-neoforge-1.21.4-1.1.23.jar |Easy Villagers |easy_villagers |1.21.4-1.1.23 |Manifest: NOSIGNATURE
inventorytotem-1.21.4-3.3.jar |Inventory Totem |inventorytotem |3.3 |Manifest: NOSIGNATURE
Jade-1.21.4-NeoForge-17.1.2.jar |Jade |jade |17.1.2+neoforge |Manifest: NOSIGNATURE
justenoughbreeding-neoforge-1.21.4-1.5.0.jar |Just Enough Breeding |justenoughbreeding |1.5.0 |Manifest: NOSIGNATURE
just-hammers-neoforge-21.4.0.jar |Just Hammers |justhammers |21.4.0 |Manifest: NOSIGNATURE
kffmod-5.7.0.jar |Kotlin For Forge |kotlinforforge |5.7.0 |Manifest: NOSIGNATURE
kuma-api-neoforge-21.4.4+1.21.4.jar |KumaAPI |kuma_api |21.4.4 |Manifest: NOSIGNATURE
client-1.21.4-20241203.161809-srg.jar |Minecraft |minecraft |1.21.4 |Manifest: a1:d4:5e:04:4f:d3:d6:e0:7b:37:97:cf:77:b0:de:ad:4a:47:ce:8c:96:49:5f:0a:cf:8c:ae:b2:6d:4b:8a:3f
mob_armor_trims-2.4.4+1.21.2-neoforge.jar |Mob Armor Trims |mob_armor_trims |2.4.4 |Manifest: NOSIGNATURE
modular-routers-13.4.0+mc1.21.4-13.4.0.jar |Modular Routers |modularrouters |13.4.0 |Manifest: NOSIGNATURE
MouseTweaks-neoforge-mc1.21.3-2.26.1.jar |Mouse Tweaks |mousetweaks |2.26.1 |Manifest: NOSIGNATURE
neoforge-21.4.43-beta-universal.jar |NeoForge |neoforge |21.4.43-beta |Manifest: NOSIGNATURE
resource_backpacks-neoforge-1.21.4-0.10.7-BETA.jar|Resource Backpacks |resource_backpacks |0.10.7-BETA |Manifest: NOSIGNATURE
resourceconfigapi-neoforge-1.21-2.1.5.jar |Resource Config API |resourceconfigapi |1.21-2.1.5 |Manifest: NOSIGNATURE
resourcelibrary-neoforge-1.21.4-2.4.5.jar |Resource Library |resourcelibrary |1.21.4-2.4.5 |Manifest: NOSIGNATURE
RoughlyEnoughItems-18.0.796-neoforge.jar |Roughly Enough Items (REI) |roughlyenoughitems |18.0.796 |Manifest: NOSIGNATURE
shulkerboxtooltip-neoforge-5.2.2+1.21.4.jar |ShulkerBoxTooltip |shulkerboxtooltip |5.2.2+1.21.4 |Manifest: NOSIGNATURE
spark-1.10.121-neoforge.jar |spark |spark |1.10.121 |Manifest: NOSIGNATURE
Storage Drawers-neoforge-1.21.4-15.0.0.jar |Storage Drawers |storagedrawers |15.0.0 |Manifest: NOSIGNATURE
supermartijn642configlib-1.1.8-neoforge-mc1.21.jar|SuperMartijn642's Config Libra|supermartijn642configlib |1.1.8 |Manifest: NOSIGNATURE
waystones-neoforge-1.21.4-21.4.1.jar |Waystones |waystones |21.4.1 |Manifest: NOSIGNATURE
Xaeros_Minimap_24.7.1_NeoForge_1.21.4.jar |Xaero's Minimap |xaerominimap |24.7.1 |Manifest: NOSIGNATURE
Crash Report UUID: 9ceeab38-8bc3-4bc1-8716-7a825016238c
FML: 6.0.4
NeoForge: 21.4.43-beta

this issue seems to be introduced in 65a6de6#diff-17b5346b7751d307bcff68a78a64a459432c4fea0cad7f58903e6e8cee8c21d8L56-L62, causing the mod's accesswidener to not be applied properly (the jar still contains betteradvancements.accesswidener)

a solution for now would be to just use the 1.21.3 jar on 1.21.4, it should work perfectly fine