Pixelmon Extra's problem

Hi i play pixelmon on a aternos server. I play on pixelmon generations version 8.3.0 and play on 1.12.2 forge. When i try and had pixelmon extra's via aternos the server just crashes. without it the server works but i dont have the extra's like (iv check). Does somebody know solution to this? here is the crash report.

---- Minecraft Crash Report ----

WARNING: coremods are present:
  EarlyLoadPlugin (pixelmon-generations-8.3.0.jar)
Contact their authors BEFORE contacting forge

// Don't be sad. I'll do better next time, I promise!

Time: 2/22/21 1:11 PM
Description: Exception in server tick loop

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Pixel Extras (pixelextras)
Caused by: java.lang.NoClassDefFoundError: com/pixelmonmod/pixelmon/api/events/BreedEvent$MakeEgg
    at com.pixelextras.PixelExtras.onServerStart(PixelExtras.java:58)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:637)
    at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
    at com.google.common.eventbus.Subscriber$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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
    at com.google.common.eventbus.EventBus.post(EventBus.java:217)
    at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136)
    at net.minecraftforge.fml.common.Loader.serverStarting(Loader.java:773)
    at net.minecraftforge.fml.common.FMLCommonHandler.handleServerStarting(FMLCommonHandler.java:299)
    at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:371)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:681)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: com.pixelmonmod.pixelmon.api.events.BreedEvent$MakeEgg
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
    ... 35 more
Caused by: java.lang.NullPointerException

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

-- System Details --
Details:
    Minecraft Version: 1.12.2
    Magma Version: b2a81d7
    Operating System: Linux (amd64) version 5.4.0-52-generic
    Java Version: 1.8.0_272, Oracle Corporation
    Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 949406072 bytes (905 MB) / 1373110272 bytes (1309 MB) up to 1677721600 bytes (1600 MB)
    JVM Flags: 3 total; -XX:MaxMetaspaceSize=200M -Xmx1800M -Xms900M
    IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
    FML: MCP 9.42 Powered by Forge 14.23.5.2855 8 mods loaded, 8 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 |
    |:------- |:--------------- |:------------ |:--------------------------------------------- |:--------- |
    | LCHIJA  | minecraft       | 1.12.2       | minecraft.jar                                 | None      |
    | LCHIJA  | mcp             | 9.42         | minecraft.jar                                 | None      |
    | LCHIJA  | aearlymodloader | 8.3.0        | minecraft.jar                                 | None      |
    | LCHIJA  | FML             | 8.0.99.99    | server.jar                                    | None      |
    | LCHIJA  | forge           | 14.23.5.2855 | server.jar                                    | None      |
    | LCHIJA  | biomesoplenty   | 7.0.1.2444   | BiomesOPlenty-1.12.2-7.0.1.2444-universal.jar | None      |
    | LCHIJA  | pixelmon        | 8.3.0        | pixelmon-generations-8.3.0.jar                | None      |
    | LCHIJAE | pixelextras     | 2.5.11       | pixelmonextras-2.5.11-1.12.2.jar              | None      |

    Loaded coremods (and transformers): 
EarlyLoadPlugin (pixelmon-generations-8.3.0.jar)
  com.pixelmongenerations.core.plugin.PixelmonTransformer
    Profiler Position: N/A (disabled)
    Player Count: 0 / 20; []
    Is Modded: Definitely; Server brand changed to 'Magma'
    Type: Dedicated Server (map_server.txt)