Class loading errors on Citadel 1.8.1 (Forge 36.2.4)

[GitFrog1234]

NEVERMIND, IGNORE THIS ISSUE, I WAS AN IDIOT AND DOWNLOADED THE WRONG FILE.

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I'm using Forge ver36.2.4, installed on Minecraft ver1.16.5. I have no resource or data packs installed, and the only thing in my mods folder is citadel-1.8.1-deobf.jar.
If it makes a difference, I edited the Forge profile in the launcher so it can use 8 GB of RAM instead of the default 2 - although I tried with 2 afterward and got the same result.

Whenever I try to run the game, it gives me the following message:

The crash log is as follows:

crash-2021-09-02_14.46.05-fml.txt

---- Minecraft Crash Report ----
// You're mean.

Time: 9/2/21 2:46 PM
Description: Mod loading error has occurred

java.lang.Exception: Mod Loading has failed
at net.minecraftforge.fml.CrashReportExtender.dumpModLoadingCrashReport(CrashReportExtender.java:85) [?:?] {re:classloading}
at net.minecraftforge.fml.client.ClientModLoader.completeModLoading(ClientModLoader.java:188) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.lambda$null$1(Minecraft.java:508) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft$$Lambda$3641/1379186202.run(Unknown Source) [?:?] {}
at net.minecraft.util.Util.func_215077_a(Util.java:320) [?:?] {re:classloading}
at net.minecraft.client.Minecraft.lambda$new$2(Minecraft.java:504) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft$$Lambda$3422/701760998.accept(Unknown Source) [?:?] {}
at net.minecraft.client.gui.ResourceLoadProgressGui.func_230430_a_(ResourceLoadProgressGui.java:113) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.client.renderer.GameRenderer.func_195458_a(GameRenderer.java:481) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.func_195542_b(Minecraft.java:976) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:607) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.main.Main.main(Main.java:184) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_51] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.5-36.2.4.jar:36.2] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$433/397309480.call(Unknown Source) [forge-1.16.5-36.2.4.jar:36.2] {}
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?] {}

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

-- Head --
Thread: Render thread
Stacktrace:
at com.github.alexthe666.citadel.Citadel.(Citadel.java:64) ~[?:?] {re:classloading}
-- MOD citadel --
Details:
Mod File: citadel-1.8.1-deobf.jar
Failure message: Citadel has class loading errors
java.lang.NoSuchMethodError: net.minecraft.item.Item$Properties.maxStackSize(I)Lnet/minecraft/item/Item$Properties;
Mod Version: 1.8.1
Mod Issue URL: https://github.com/Alex-the-666/Citadel/issues
Exception message: java.lang.NoSuchMethodError: net.minecraft.item.Item$Properties.maxStackSize(I)Lnet/minecraft/item/Item$Properties;
Stacktrace:
at com.github.alexthe666.citadel.Citadel.(Citadel.java:64) ~[?:?] {re:classloading}
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_51] {}
at java.lang.Class.forName(Class.java:348) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.javafmlmod.FMLModContainer.(FMLModContainer.java:61) ~[?:36.2] {re:classloading}
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_51] {}
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[?:1.8.0_51] {}
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_51] {}
at java.lang.reflect.Constructor.newInstance(Constructor.java:422) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.javafmlmod.FMLJavaModLanguageProvider$FMLModTarget.loadMod(FMLJavaModLanguageProvider.java:76) ~[?:36.2] {re:classloading}
at net.minecraftforge.fml.ModLoader.buildModContainerFromTOML(ModLoader.java:302) ~[?:?] {re:classloading}
at net.minecraftforge.fml.ModLoader.lambda$buildMods$29(ModLoader.java:281) ~[?:?] {re:classloading}
at net.minecraftforge.fml.ModLoader$$Lambda$3035/1691678663.apply(Unknown Source) ~[?:?] {}
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[?:1.8.0_51] {}
at java.util.HashMap$EntrySpliterator.forEachRemaining(HashMap.java:1683) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502) ~[?:1.8.0_51] {}
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_51] {}
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.ModLoader.buildMods(ModLoader.java:283) ~[?:?] {re:classloading}
at net.minecraftforge.fml.ModLoader.lambda$gatherAndInitializeMods$11(ModLoader.java:183) ~[?:?] {re:classloading}
at net.minecraftforge.fml.ModLoader$$Lambda$3032/269257589.apply(Unknown Source) ~[?:?] {}
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[?:1.8.0_51] {}
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[?:1.8.0_51] {}
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502) ~[?:1.8.0_51] {}
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[?:1.8.0_51] {}
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_51] {}
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.ModLoader.gatherAndInitializeMods(ModLoader.java:185) ~[?:?] {re:classloading}
at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$1(ClientModLoader.java:103) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraftforge.fml.client.ClientModLoader$$Lambda$2896/1687702287.run(Unknown Source) ~[?:?] {}
at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$4(ClientModLoader.java:123) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraftforge.fml.client.ClientModLoader$$Lambda$2897/690051320.run(Unknown Source) ~[?:?] {}
at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:103) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.client.Minecraft.(Minecraft.java:437) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.main.Main.main(Main.java:149) [?:?] {re:classloading,pl:runtimedistcleaner:A}
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_51] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51] {}
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.5-36.2.4.jar:36.2] {}
at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$433/397309480.call(Unknown Source) [forge-1.16.5-36.2.4.jar:36.2] {}
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?] {}

-- System Details --
Details:
Minecraft Version: 1.16.5
Minecraft Version ID: 1.16.5
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 4577898552 bytes (4365 MB) / 8287944704 bytes (7904 MB) up to 8589934592 bytes (8192 MB)
CPUs: 8
JVM Flags: 10 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -XX:+IgnoreUnrecognizedVMOptions -Xmx8G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
ModLauncher: 8.0.9+86+master.3cf110c
ModLauncher launch target: fmlclient
ModLauncher naming: srg
ModLauncher services:
/mixin-0.8.2.jar mixin PLUGINSERVICE
/eventbus-4.0.0.jar eventbus PLUGINSERVICE
/forge-1.16.5-36.2.4.jar object_holder_definalize PLUGINSERVICE
/forge-1.16.5-36.2.4.jar runtime_enum_extender PLUGINSERVICE
/accesstransformers-3.0.1.jar accesstransformer PLUGINSERVICE
/forge-1.16.5-36.2.4.jar capability_inject_definalize PLUGINSERVICE
/forge-1.16.5-36.2.4.jar runtimedistcleaner PLUGINSERVICE
/mixin-0.8.2.jar mixin TRANSFORMATIONSERVICE
/forge-1.16.5-36.2.4.jar fml TRANSFORMATIONSERVICE
FML: 36.2
Forge: net.minecraftforge:36.2.4
FML Language Providers:
javafml@36.2
minecraft@1
Mod List:
forge-1.16.5-36.2.4-client.jar |Minecraft |minecraft |1.16.5 |NONE |Manifest: NOSIGNATURE
forge-1.16.5-36.2.4-universal.jar |Forge |forge |36.2.4 |NONE |Manifest: 22:af:21:d8:19:82:7f:93:94:fe:2b:ac:b7:e4:41:57:68:39:87:b1:a7:5c:c6:44:f9:25:74:21:14:f5:0d:90
citadel-1.8.1-deobf.jar |Citadel |citadel |1.8.1 |NONE |Manifest: NOSIGNATURE

[Tizyfox]

what have you done to solve it?

[GitFrog1234]

I downloaded and used the citadel-1.8.1-1.16.5.jar file instead of citadel-1.8.1-deobf.jar, found on the mod's Files tab on CurseForge.