DaemonUmbra

Delete the forge config files and try again

Pre-1.13 Forge only works with Java 8.

I don't even see an issue here. and I think this is where we have to call it anyway, sorry.

What launcher are you using? Please provide a screenshot. Please read the Logs section of my signature below and provide the appropriate log in the appropriate manner.

Why are you using such an old version of Forge for 1.12.2 anyway?

1.10.2 at this point should be considered end-of-life. Update to 1.14.4

How did you install Forge?

Don't use MCreator.

1.7.10 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

It sounds like you're trying to use Spigot plugins with Forge mods, I would recommend you use Sponge if you need to use plugins because it is designed to work with Forge to a degree.

Please read the Logs section of my signature below and provide the appropriate log in the appropriate manner.

Forge installs itself as a version of Minecraft. Make a new Profile/Installation and select Forge from the version dropdown. (Note: For some reason Forge 1.12.2 gets booted to the bottom of the list.)

Try removing Erebus entirely

Are you playing in single player or on a server?

This is not how things work, the 1.12.2 server is the 1.12.2 server. Unlikely. I would guess that the problem is somewhere in here before I suspect it would be in vanilla, unless you can reproduce this crash in vanilla.

1.7.10 is no longer supported on this forum due to its age. Please update to a modern version of Minecraft to receive support.

...the jar file IS the installer. Don't extract it, run it with Java. If you don't have Java installed get it from here: https://adoptopenjdk.net If you have Java or just installed it and the jar is being associated with WinRar instead of Java, try this: https://johann.loefflmann.net/en/software/jarfix/index.html

Why do people always assume more ram is the solution? No, this is probably a latency issue between you and the server.

Please read the Logs section of my signature below and provide the appropriate log in the appropriate manner.

So you're saying you haven't bought the game yet. Buy the game and you'll have a username you can set.

What launcher are you using? Please provide a screenshot.

More likely the client component of the mod is showing you the modded blocks and items in the creative menu because you have the mods installed on your client, but as soon as you join the server and try to spawn blocks or items from the mods it won't work.

and a screenshot of the 1.12.2 folder that's in your mods folder...

Send a screenshot of your mods folder please?

In a 1.12.2 folder in your mods folder