Describe the bug
I was trying to create a modded server but sophisticated backpacks failed to load correctly, I tried changing downloading another version of the mod to a newer one but it didn't work.

Crash log

-- Head --
Thread: main
Stacktrace:
at net.minecraftforge.eventbus.EventBus.getEventClass(EventBus.java:220) ~[eventbus-4.0.0.jar:?] {}
-- MOD sophisticatedbackpacks --
Details:
Mod File: sophisticatedbackpacks-1.16.4-2.4.0.259.jar
Failure message: Sophisticated Backpacks (sophisticatedbackpacks) has failed to load correctly
java.lang.IllegalStateException: Failed to resolve consumer event type: net.p3pp3rf1y.sophisticatedbackpacks.common.CommonProxy$$Lambda$3323/0x000000001374f1c0@8446fb16
Mod Version: property(class java.lang.String, provider(?))
Mod Issue URL: https://github.com/P3pp3rF1y/SophisticatedBackpacks/issues
Exception message: java.lang.IllegalStateException: Failed to resolve consumer event type: net.p3pp3rf1y.sophisticatedbackpacks.common.CommonProxy$$Lambda$3323/0x000000001374f1c0@8446fb16
Stacktrace:
at net.minecraftforge.eventbus.EventBus.getEventClass(EventBus.java:220) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.checkNotGeneric(EventBus.java:162) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:173) ~[eventbus-4.0.0.jar:?] {}
at net.p3pp3rf1y.sophisticatedbackpacks.common.CommonProxy.registerHandlers(CommonProxy.java:65) ~[sophisticatedbackpacks:property(class java.lang.String, provider(?))] {re:classloading}
at net.p3pp3rf1y.sophisticatedbackpacks.SophisticatedBackpacks.(SophisticatedBackpacks.java:41) ~[sophisticatedbackpacks:property(class java.lang.String, provider(?))] {re:classloading}
at java.lang.J9VMInternals.newInstanceImpl(Native Method) ~[?:1.8.0_282] {}
at java.lang.Class.newInstance(Class.java:2015) ~[?:1.8.0_282] {}
at net.minecraftforge.fml.javafmlmod.FMLModContainer.constructMod(FMLModContainer.java:81) ~[forge:36.1] {re:classloading}
at net.minecraftforge.fml.javafmlmod.FMLModContainer$$Lambda$3112/0x0000000000000000.run(Unknown Source) ~[?:?] {}
at net.minecraftforge.fml.ModContainer.lambda$buildTransitionHandler$4(ModContainer.java:120) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.ModContainer$$Lambda$3268/0x0000000000000000.run(Unknown Source) ~[?:?] {}
at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1640) ~[?:1.8.0_282] {}
at java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1632) ~[?:1.8.0_282] {}
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[?:1.8.0_282] {}
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) ~[?:1.8.0_282] {}
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692) ~[?:1.8.0_282] {re:computing_frames}
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:175) ~[?:1.8.0_282] {}

System Details

Details:
Minecraft Version: 1.16.5
Minecraft Version ID: 1.16.5
Operating System: Windows 8.1 (amd64) version 6.3
Java Version: 1.8.0_282, AdoptOpenJDK
Java VM Version: Eclipse OpenJ9 VM (JRE 1.8.0 Windows 8.1 amd64-64-Bit Compressed References 20210120_972 (JIT enabled, AOT enabled)
OpenJ9 - 345e1b09e
OMR - 741e94ea8
JCL - ab07c6a8fd based on jdk8u282-b08), Eclipse OpenJ9
Memory: 8581619432 bytes (8184 MB) / 10737418240 bytes (10240 MB) up to 24696061952 bytes (23552 MB)
CPUs: 8
JVM Flags: 23 total; -Xoptionsfile=C:\Program Files\AdoptOpenJDK\jdk-8.0.282.8-openj9\jre\bin\compressedrefs\options.default -Xlockword:mode=default,noLockword=java/lang/String,noLockword=java/util/MapEntry,noLockword=java/util/HashMap$Entry,noLockword=org/apache/harmony/luni/util/ModifiedMap$Entry,noLockword=java/util/Hashtable$Entry,noLockword=java/lang/invoke/MethodType,noLockword=java/lang/invoke/MethodHandle,noLockword=java/lang/invoke/CollectHandle,noLockword=java/lang/invoke/ConstructorHandle,noLockword=java/lang/invoke/ConvertHandle,noLockword=java/lang/invoke/ArgumentConversionHandle,noLockword=java/lang/invoke/AsTypeHandle,noLockword=java/lang/invoke/ExplicitCastHandle,noLockword=java/lang/invoke/FilterReturnHandle,noLockword=java/lang/invoke/DirectHandle,noLockword=java/lang/invoke/ReceiverBoundHandle,noLockword=java/lang/invoke/DynamicInvokerHandle,noLockword=java/lang/invoke/FieldHandle,noLockword=java/lang/invoke/FieldGetterHandle,noLockword=java/lang/invoke/FieldSetterHandle,noLockword=java/lang/invoke/StaticFieldGetterHandle,noLockword=java/lang/invoke/StaticFieldSetterHandle,noLockword=java/lang/invoke/IndirectHandle,noLockword=java/lang/invoke/InterfaceHandle,noLockword=java/lang/invoke/VirtualHandle,noLockword=java/lang/invoke/PrimitiveHandle,noLockword=java/lang/invoke/InvokeExactHandle,noLockword=java/lang/invoke/InvokeGenericHandle,noLockword=java/lang/invoke/VarargsCollectorHandle,noLockword=java/lang/invoke/ThunkTuple -Xjcl:jclse29 -Xms10G -Xmx23G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:-OmitStackTraceInFastThrow -XX:+AlwaysPreTouch -XX:G1NewSizePercent=40 -XX:G1MaxNewSizePercent=50 -XX:G1HeapRegionSize=16M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=8 -XX:InitiatingHeapOccupancyPercent=20 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:MaxTenuringThreshold=1
ModLauncher: 8.0.9+86+master.3cf110c
ModLauncher launch target: fmlserver
ModLauncher naming: srg
ModLauncher services:
/mixin-0.8.2.jar mixin PLUGINSERVICE
/eventbus-4.0.0.jar eventbus PLUGINSERVICE
/forgeserver.jar object_holder_definalize PLUGINSERVICE
/forgeserver.jar runtime_enum_extender PLUGINSERVICE
/accesstransformers-3.0.1.jar accesstransformer PLUGINSERVICE
/forgeserver.jar capability_inject_definalize PLUGINSERVICE
/forgeserver.jar runtimedistcleaner PLUGINSERVICE
/mixin-0.8.2.jar mixin TRANSFORMATIONSERVICE
/preview_OptiFine_1.16.5_HD_U_G8_pre11.jar OptiFine TRANSFORMATIONSERVICE
/forgeserver.jar fml TRANSFORMATIONSERVICE
FML: 36.1
Forge: net.minecraftforge:36.1.0
FML Language Providers:
[email protected]
minecraft@1

To Reproduce
Steps to reproduce the behavior:

1. Create Server
2. Open Server
3. Crash

Expected behavior
Expected to generate world normally

Versions
Mod: sophisticatedbackpacks-1.16.4-2.4.0.259.jar
Forge version: 36.0.1

Forge isn't compatible with OpenJ9 JDK so you need to use a different one. As far as I know pretty much any other works. Nothing I can do about this on my side as it's an issue with how OpenJ9 loads classes which then breaks Forge functionality that registers event listeners from mods.