DaemonUmbra

That sounds like an issue with your IDE not finding Forge, close your ide and delete all project files and reimport it

If you're saying "Yes I still have the issue without Immersive Portals installed", can you provide a log without immersive portals installed?

Just get the new installer, run it, and change your launcher installation to use the new version

Please provide debug.log as described in the EAQ and the logs section of my signature below

1.8 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Is this a repost of your other thread?

The eula will pop up with Forge as well

1.7 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Do you still have the issue without immersive portals installed?

You know you're starting a vanilla server, right?

I don't understand what the issue is

1.7 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Delete fml.toml and let the game regenerate it from default

Don't make jarmods, and 1.12.2 is no longer supported.

Please provide debug.log as described in the EAQ and the logs section of my signature below

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

What are you talking about? Mods haven't been in the .zip format for years, and you're supposed to put mods into the mods folder, they don't magically appear there.

Mods aren't compatible across Minecraft versions. You can use 1.12.2 if you want, but we won't be helping you if it breaks

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

Are you already running a server?

Did you change the game directory for your Forge profile?

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.

If by "what do I do now?" you mean "how do I get Decocraft for 1.15.2?" I'm sorry to say that you have to wait and see if it gets updated to 1.15.2

Check the Optifine changelog for the version of Forge it's designed to be compatible with