DaemonUmbra

Why are you even using the old launcher? Use the native launcher.

If you are using an IDE you should NEVER need to root around in the gradle cache manually, both Eclipse and Intellij link it as a dependency so you can browse it as such

I get suspicious when people say "same error" because often times it's not and they can't tell the difference

Please read my signature below, Logs section, Twitch Launcher sub-section, you'll find instructions and a video on how to run a Twitch modpack without Twitch applying its launcher tweaks

https://github.com/MinecraftForge/InstallerTools/pull/1 Edit: I misread

It's the thing below each of my posts, but it's not visible on mobile

Looks like an issue with aether, make sure you're running the latest version and if you are, report it to the author.

Please provide your installer log, it will have the same name as the installer but with .log on the end: Installer: forge-{version}-installer.jar Log: forge-{version}-installer.jar.log Note: If you have Windows Explorer set to hide file extensions(as is the default setting), they will look like this: Installer: forge-{version}-installer Log: forge-{version}-installer.jar

Please read my signature for information on why you should NOT be getting your mods from 9Minecraft

Where are you getting your mods?

Have you restarted the launcher since you got the error? If so please restart the launcher and reproduce the error, then shut down the launcher and provide the updated launcher_log.txt

Please provide your launcher_log.txt from .minecraft

Please read my signature for info on why this is a bad thing

Wait, you're trying to backdate a mod from 1.12 to 1.8.9? Yeah 1.8.9 is no longer supported on this forum due to its age.

Use the modern launcher

Make sure you have not run the launcher since the crash/failed launch, go to .minecraft and post your launcher_log.txt

Check the "Logs" section of my signature, "Twitch Launcher" sub-section, you'll find instructions and a video on how to launch a Twitch Modpack without having Twitch apply its launcher tweaks

Delete the file it indicates, run the Minecraft Launcher, then try the installer again.

Please provide your debug.log if it exists, otherwise check .minecraft and provide launcher_log.txt

Please do not hijack threads, if you have an issue please make your own.

https://github.com/Microsoft/vscode-arduino/issues/644#issuecomment-415329398

Please provide your installer log, it will have the same name as the installer but with .log on the end: Installer: forge-{version}-installer.jar Log: forge-{version}-installer.jar.log Note: If you have Windows Explorer set to hide file extensions(as is the default setting), they will look like this: Installer: forge-{version}-installer Log: forge-{version}-installer.jar

Chances are you're running a HEAVY modpack on a cheaper (less powerful) host package.