quadraxis

That isn't the case - https://github.com/MinecraftForge/MinecraftForge/pull/5129 makes it so that there may a warning logged for the offending mod(s).

Please upload the latest.log file from when this occurs to Pastebin/Gist/similar and link it here.

MapColor is not an enum. However, it is not a good idea to try adding additional instances, as there are only a few available slots for them, and no way of avoiding ID collisions. In any case, returning a new instance from the getter is also incorrect, a fixed value should be used.

[main/DEBUG] [FML]: Loaded 89 rules from AccessTransformer config file forge_at.cfg This appears to be missing entries (I see 213 when launching 2768). Can you try redownloading and reinstalling Forge?

A mostly-complete spec can be found here: https://gist.github.com/RainWarrior/0618131f51b8d37b80a6

Is the server running Sponge? If so, please see https://github.com/SpongePowered/SpongeForge/issues/2525.

[22:06:10] [main/INFO] [Hammer Core [ASM]]: Transforming net.minecraftforge.client.ForgeHooksClient (net.minecraftforge.client.ForgeHooksClient)... [22:06:10] [main/INFO] [Hammer Core [ASM]]: -Patching ForgeHooksClient [22:06:10] [main/INFO] [STDOUT]: [com.creativemd.creativecore.transformer.CreativeTransformer:transform:49]: [littletiles] Patched net.minecraftforge.client.ForgeHooksClient ... [22:06:10] [main/INFO] [STDOUT]: [team.chisel.ctm.client.asm.CTMTransformer:preTransform:230]: Transforming Class [net.minecraftforge.client.ForgeHooksClient], Method [getDamageModel] [22:06:10] [main/INFO] [STDOUT]: [team.chisel.ctm.client.asm.CTMTransformer:finishTransform:242]: Transforming net.minecraftforge.client.ForgeHooksClient Finished. [22:06:10] [main/ERROR] [LaunchWrapper]: Unable to launch Most likely an issue with a coremod you have installed. Try removing the above mods one at a time and seeing if the game starts correctly.

This is a Forge issue. An update will probably be released soon to fix it, in the meantime use build 2789 (click "Show all Versions").

Update Thaumcraft, you may also want to make sure that the other mods you are using are up-to-date.

findField calls setAccessible(true) itself, it doesn't need to be called here at all. Also, update Forge and use ObfuscationReflectionHelper.findField with only the SRG name (field_184560_g).

Try adding -Dforge.logging.mojang.level=debug to the server run arguments (and possibly also your client JVM arguments) and then supply a debug.log file with that setting enabled to get more info than just "Can't serialize unregistered packet".

Description: FML has discovered extracted jar files in the mods directory. This breaks mod loading functionality completely. Remove the directories and replace with the jar files originally provided.  This is fairly self-explanatory - all mods in your mods folder should be .jar files, don't "extract" them or anything else like that.

It looks like you're using a 32-bit version of Java here: c:\Program Files (x86)\Java\jdk1.8.0_192 Use the 64-bit version instead - as your PC has >4GB ram, this should be supported.

Please upload the whole file to a text-hosting site like Pastebin or Gist.

Update CTM: https://github.com/Chisel-Team/ConnectedTexturesMod/issues/84

You need to use Java 8.

https://github.com/MinecraftForge/MinecraftForge/issues/5207

I'm not the author of the mod, I'm simply repeating what they have previously said. If you want to debate it, you can find them on various modding Discords, among other places.

Try using the latest Optifine version for 1.12.2 first, and if it doesn't work, you'll need to report it to them and ask them to fix it. https://github.com/sp614x/optifine/issues

https://minecraft.curseforge.com/projects/botania-tweaks had difficulty with a number of things due to the base mod not using ObjectHolders.

Not the issue: forge-1.12.2-14.23.5.2772.jar Most likely a problem with a coremod, probably Optifine.

Well it looks likely to be either MicdoodleCore or Optifine. Try updating Forge first. Optifine, by its nature, does not have good compatibility across different Forge versions.

If you're using CTM, please refer to https://github.com/Chisel-Team/ConnectedTexturesMod/issues/84.

Exception in thread "main" java.lang.ClassCastException: java.base/jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to java.base/java.net.URLClassLoader Java 9+ is not currently supported, you need to use Java 8.

Does it work without Optifine?