net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Pixelmon (pixelmon)

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 8/18/19 1:08 PM
Description: There was a severe problem during mod loading that has caused the game to fail

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Pixelmon (pixelmon)
Caused by: java.lang.NoSuchMethodError: net.minecraftforge.fml.relauncher.ReflectionHelper.getPrivateValue(Ljava/lang/Class;Ljava/lang/Object;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
at com.pixelmonmod.pixelmon.entities.pixelmon.EntityPixelmon.<clinit>(EntityPixelmon.java:91)
at com.pixelmonmod.pixelmon.CommonProxy.registerInteractions(CommonProxy.java:220)
at com.pixelmonmod.pixelmon.Pixelmon.init(Pixelmon.java:163)
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:497)
at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:624)
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:497)
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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:218)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:196)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$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:135)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:744)
at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:336)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:534)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
at net.minecraft.client.main.Main.main(SourceFile:123)
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:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)


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: 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: 302063712 bytes (288 MB) / 805306368 bytes (768 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.42 Powered by Forge 14.23.5.2768 5 mods loaded, 5 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 |
|:----- |:--------- |:------------ |:----------------------------------- |:---------------------------------------- |
| UCHI | minecraft | 1.12.2 | minecraft.jar | None |
| UCHI | mcp | 9.42 | minecraft.jar | None |
| UCHI | FML | 8.0.99.99 | forge-1.12.2-14.23.5.2768.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHI | forge | 14.23.5.2768 | forge-1.12.2-14.23.5.2768.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHEE | pixelmon | 7.0.7 | Pixelmon-1.12.2-7.0.7-universal.jar | None |

Loaded coremods (and transformers):
GL info: ' Vendor: 'Intel' Version: '4.5.0 - Build 25.20.100.6518' Renderer: 'Intel(R) HD Graphics 520'

Thanks for the report.

This is not a bug, but rather a side effect of Pixelmon now being built against newer Forge versions, as well as Forge's recommended build being really old. (with them moving on to newer MC versions and all)

To fix this, download and install Forge 2838, current Latest. Select it in your launcher, and this issue should be fixed. Also update Optifine to E3 if you're using that.