[10:08:41] [main/WARN] [FML]: Found FMLCorePluginContainsFMLMod marker in MrTJPCore-1.12.2-2.1.1.27-universal.jar. This is not recommended, @Mods should be in a separate jar from the coremod.
[10:08:41] [main/ERROR] [FML]: Coremod mrtjp.core.handler.CorePlugin: Unable to class load the plugin java.lang.ClassNotFoundException: mrtjp.core.handler.CorePlugin

Forge 2702

So, you don't even bother to update to the latest version of TJCore to see if the issue persists. Nice. Next time update before posting an issue.

Huh, i sware build 33 was released, anyway, its fixed in dev.
Also, appologies if i came accross like a dick, long day, frustration coming out in the wrong places..

https://minecraft.curseforge.com/projects/mrtjpcore/files

Care to tell me where to find a version newer than MrTJPCore-1.12.2-2.1.1.27-universal.jar? One of us needs glasses.