Crash on loading server.

Hello.

I'm trying to host a pixelmon reforged server on a dedicated host. 

I imported the modpack from the twitch launcher.

Assumed that would be all I need to do, however, when I load the server I get this crash report:

---- Minecraft Crash Report ----

// Why did you do that?

Time: 10/13/20 2:10 PM
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: net/minecraftforge/fml/client/CustomModLoadingErrorDisplayException
    at de.keksuccino.konkrete.Konkrete.<init>(Konkrete.java:23)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at java.lang.Class.newInstance(Class.java:442)
    at net.minecraftforge.fml.common.ILanguageAdapter$JavaAdapter.getNewInstance(ILanguageAdapter.java:191)
    at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:599)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
    at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
    at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
    at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
    at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
    at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
    at com.google.common.eventbus.EventBus.post(EventBus.java:217)
    at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219)
    at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
    at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
    at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
    at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
    at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
    at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
    at com.google.common.eventbus.EventBus.post(EventBus.java:217)
    at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136)
    at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:595)
    at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98)
    at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:333)
    at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: net.minecraftforge.fml.client.CustomModLoadingErrorDisplayException
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 39 more
Caused by: net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerException: Exception in class transformer net.minecraftforge.fml.common.asm.transformers.SideTransformer@4d6f197e from coremod FMLCorePlugin
    at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:260)
    at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279)
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176)
    ... 41 more
Caused by: java.lang.RuntimeException: Attempted to load class net/minecraftforge/fml/client/CustomModLoadingErrorDisplayException for invalid side SERVER
    at net.minecraftforge.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:62)
    at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:256)
    ... 43 more

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

-- System Details --
Details:
    Minecraft Version: 1.12.2
    Operating System: Linux (amd64) version 3.10.0
    Java Version: 1.8.0_211, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 40860032 bytes (38 MB) / 162574336 bytes (155 MB) up to 2813853696 bytes (2683 MB)
    JVM Flags: 11 total; -Xms32M -Xmx2775M -XX:OnOutOfMemoryError=curl https://api.creeper.host/callbacks/minecraft/outofmemory.php?instance=mc-5f85b4e9cb9af -k -XX:OnError=curl http://api.creeper.host/callbacks/minecraft/crash.php?instance=mc-5f85b4e9cb9af -k -XX:+UseParNewGC -XX:+UnlockExperimentalVMOptions -XX:+CMSIncrementalPacing -XX:+CMSClassUnloadingEnabled -XX:ParallelGCThreads=3 -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=10
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP 9.42 Powered by Forge 14.23.5.2854 14 mods loaded, 14 mods active
    States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

    | State | ID             | Version       | Source                                        | Signature                                |
    |:----- |:-------------- |:------------- |:--------------------------------------------- |:---------------------------------------- |
    | LC    | minecraft      | 1.12.2        | minecraft.jar                                 | None                                     |
    | LC    | mcp            | 9.42          | minecraft.jar                                 | None                                     |
    | LC    | FML            | 8.0.99.99     | forge-1.12.2-14.23.5.2854.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | LC    | forge          | 14.23.5.2854  | forge-1.12.2-14.23.5.2854.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | LC    | biomesoplenty  | 7.0.1.2444    | biomesoplenty-1.12.2-7.0.1.2444-universal.jar | None                                     |
    | LC    | bop_patch      | 1.0           | BOP-Patch-1.0.jar                             | None                                     |
    | LC    | pixelmon       | 8.1.2         | pixelmon-1.12.2-8.1.2-universal.jar           | None                                     |
    | LC    | gameshark      | 6.0.4         | Gameshark-1.12.2-6.0.4-universal.jar          | None                                     |
    | LC    | journeymap     | 1.12.2-5.7.1  | journeymap-1.12.2-5.7.1.jar                   | None                                     |
    | LC    | k4lib          | 1.12.1-2.1.81 | k4lib-1.12.1-2.1.81-universal.jar             | None                                     |
    | L     | konkrete       | 1.0.3         | konkrete1.0.3mc1.12-1.12.2.jar                | None                                     |
    | L     | naturescompass | 1.8.5         | naturescompass-1.12.2-1.8.5.jar               | None                                     |
    | L     | pixelextras    | 2.5.10        | PixelExtras-1.12.2-2.5.10-universal.jar       | None                                     |
    | L     | toomanybackups | 1.0.5         | toomanybackups-1.12.2-1.0.5.jar               | None                                     |

    Loaded coremods (and transformers): 
    Profiler Position: N/A (disabled)
    Is Modded: Definitely; Server brand changed to 'fml,forge'
    Type: Dedicated Server (map_server.txt)

Googled around but couldn't find a fix on what I've done wrong. Hopefully someone can help :) .