DaemonUmbra

Because it's what Forge targets and Forge uses internal stuff to accomplish some of its black magic, and as we've recently discovered Java 14 changes some of the internals that Forge uses. No, Forge will not update to fit Java 14 if it means dropping Java 8 compatibility.

Update JEI

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

That's latest.log, not debug.log

Can I see a log showing updated Botania AND without Optifine?

That means you have either typed the name wrong or haven't cd'ed to the directory it is in. You can google this part

Install Java 8 HotSpot https://adoptopenjdk.net

Try running the 1.15.2 installer manually from a terminal, what does it say?

There's a more recent version of Botania available for 1.14.4, try that?

I'm not going to help you with 1.10.2. If you want support you need to be using 1.14.4 or 1.15.2.

Can you show the crash without Optifine?

Please provide the full debug.log using one of the paste sites listed in my signature

Can you tell me the exact 1.15.2 version you're trying to install?

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

Or you could try removing Optifine

What version of Minecraft are you using?

You appear to be using a 1.14 version of Neat on 1.15.2, try removing it

This means you didn't have Java installed. Now you'll need to install Java 8 and assign the .jar file extension to Java rather than IE.

1.12 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. Edit: Threads merged, don't spam threads

Did this happen when you tried to resize the window before the game loaded?

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

You haven't provided a useful log yet. Start the launcher and recreate the issue, then close the launcher and send the log.

If you haven't made any config changes, delete your config folder