Modpack Troubleshooting

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Originally posted in discord, I felt like it could have its own forum post instead.

Playing Modpacks: Common Issues

When I click play in the curseforge launcher, a window pops up but the play button is stuck on Loading:

UPDATED METHOD: Go to Settings → Minecraft, and select the native launcher instead of the jar launcher. If the jar launcher option is greyed out, continue with below:

Go to twitch preferences → minecraft and take note of the minecraft path. Open this folder in file explorer or finder then go to /Install/game then replace the launcher.jar with https://launcher.mojang.com/v1/objects/eabbff5ff8e21250e33670924a0c5e38f47c840b/launcher.jar. Make sure the new jar file is named exactly installer.jar. When you launch a modpack, the top of the window/name of the launcher should say “1.6.93” (1.6.91 is the version downloaded by twitch - this one has bugs on macOS)

Clicking “Play” runs then crashes with something like "Exception in thread “main” java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader ":

UPDATED METHOD: Go to Settings → Minecraft, and select the native launcher instead of the jar launcher. If the jar launcher option is greyed out, continue with below:

Go to twitch preferences → minecraft and scroll down to java version. Make sure a java 8 version is selected.

Still doesn’t work? I recommend using multimc instead:

  1. Download multimc from https://multimc.org/ and install it.
  2. Go to the modpack you want to install on curseforge, like https://www.curseforge.com/minecraft/modpacks/rlcraft. Go to files → find the version you want and click on the name then click the Download button, not the install button. Do not download the server pack.
  3. Open multimc and click “add instance”. Choose “install from zip” and select the zip file you downloaded from step 1. Click ok and wait.
  4. You should now see the modpack in the list. Either doubleclick it or click “launch instance” to the right!

I’m using MultiMC but I can’t resize the window because the game crashes or the mouse alignment messes up!

  • Windows: Go to Settings → Java then click the ... then navigate to \Program Files (x86)\Minecraft Launcher\runtime\jre-x64\bin\java.exe
  • MacOS: while in finder, click on at the top go → go to folder then copy in ~/Library/Application Support/minecraft/runtime/jre-x64/jre.bundle/Contents/Home/bin/ and hit ok. Once you have the java file selected, go to multimc java settings then click …, and in the window that opens, drag + drop the java file into this window then hit enter.
  • Both: Click on “Test”. You should get a successful test with java version 1.8.0_74 reported.

If you’ve tried the above or if none of the above match your issue, please feel free to ask here or in discord for a fast response: https://discord.tallcraft.com

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