DaemonUmbra

It looks like you need to give Minecraft more memory

What launcher are you using? Where are you getting your mods from? How are you installing your mods?

That is the Minecraft version, not the Forge version I would assume if you are playing the pack you got it from the Twitch launcher which should have installed the correct version for you.

You're not using the Forge version that the pack is intended to be used with.

If you're running a server and it crashes with java.lang.NoClassDefFoundError: net/minecraft/client/anything it is because the mod tried to use code that only exists in the client, not the server

Is there a reason this has to be client-side-only?

What happens is when Mojang release a version or snapshot they run it through an obfuscator, this renames everything to what looks like gibberish and no longer has the same organization system (the hierarchy of files and folders is flattened) but is still valid code, some obfuscators go a step further and make slight tweaks to make things more efficient, an example of this is it might remove code that is never accessed (This is what creates the difference between the client and server with code that both use).

That paste does not exist

Extra Golems appears to be broken.

Have you tried running the installer since you made this post? The log mentions connection timeouts which may have been the product of your internet going down the tubes at that moment.

That appears to be it, how good is the internet connection on the machine you are installing Forge on?

Bonfires appears to be the cause.

User was banned for using a cracked launcher.

One of your mods says otherwise...

No, you want to remove minecraft_server.1.12.2.jar from the bat file and replace it with the name of the forge jar which I don't feel like transcribing from your image. Also, where are you getting your mods?

Well there you go, you're starting a vanilla server. Replace minecraft_server.1.12.2.jar with the forge jar.

What are the contents of start.bat? What is in the mods folder of the server?

You should never download mods from just random sites, please delete every mod you have and start over with these changes: Only download Forge from https://files.minecraftforge.net/ Only download Mods from https://minecraft.curseforge.com Install the StopModReposts browser extension

Where are you getting your mods?

Try removing safeplace

I'm afraid the best you can do is make sure all your mods are up to date or use the same version of Forge they worked with previously. Coremods are notorious for causing issues that can't be reliably traced back to the offending mod.

You have too many Coremods to really say this is a Forge issue, can you recreate the crash with Forge alone?

Please read the "Logs" section of my signature (or the EAQ sticked at the top of the subforum) and post your debug.log

Forge only works with Minecraft Java Edition, if you got it through the MS Store it is Bedrock Edition.

https://mcforge.readthedocs.io/en/latest/events/intro/ For information on what events are available, use your IDE to dig through the net.minecraftforge.event package.