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Using custom Java versions

Legacy Launcher uses Mojang's recommended Java builds by Microsoft. This guide will help you to replace these Java versions with the ones of your choice.

info

This page requires localization of screenshots. Feel free to open PR if you want to help

How to?​

  1. Install required Minecraft version
  2. Open launcher settings, select "Minecraft" tab and open Java settings Settings => Minecraft => Java => Java => "Customize"
  3. Select "Recommended" option Select "Recommended" Java
  4. Click "open folder" Open folder
  5. In the folder, create a file named override, e.g. override.txt Creating an override file
  6. Done! This Java version is customized, and can be freely modified or replaced
Where I can get alternative Java distributions?

You can download alternate Java distributions from their developers' websites, such as Temurin and Azul. You should download the archive, not the installer.

Simplified method​

Due to complaints about the stability of Mojang recommended Java builds we have prepared a ready-to-use package to replace Java with more stable ones.

  1. Download the archive:
  2. Open the launcher settings, select "Minecraft" tab and go to Java settings Settings => Minecraft => Java => Java => "Customize".
  3. In the window that opens, select the "Recommended" option Select "Recommended" Java
  4. Click "Open Folder" Open folder
  5. In the opened folder, twice move up a level.
    tip

    If you see folders named java-runtime-alpha, java-runtime-beta, java-runtime-gamma, jre-legacy then you have done everything correctly

    warning

    If you see the .version file next to a folder and/or don't see any other Java folders, or see lib and bin folders - you're probably in the wrong folder

  6. Replace folder contents with the one from the downloaded archive.
  7. Run the launcher and the game

Setting custom JRE using the launcher settings​

This method is not recommended

This method will override Java for all Minecraft versions. Make sure you switched Java back to "Recommended" when changing Minecraft version or modpack!

  1. Download and install required Java version
  2. Open the launcher settings, select "Minecraft" tab and go to Java settings Settings => Minecraft => Java => Java => "Customize".
  3. In the window that opens, select the "Custom" option
  4. Click "Browse" button near the Path field and select bin/java.exe (for Windows) or bin/java (for Linux/macOS) executable for installed Java version
    Default Java install locations

    Windows: Check Java installer settings. In most cases it will install Java to C:\Windows\Program Files
    Linux: Most package managers will install Java under /usr/lib/jvm path
    macOS: In most cases you'll find installed Java under /Library/Java/JavaVirtualMachines and ~/Library/Java/JavaVirtualMachines paths

    warning

    When pasting Java path manually make sure there are no quotes surrounding the path

  5. Click "Done" button

The Hard Way​

warning

This method is recommended for experienced users only

tip

This method is recommended for modpacks and custom versions

  1. Start Legacy Launcher
  2. Click "Open game folder" (the one with folder icon) button to open game folder Click the button with folder icon
    • Launcher may ask you to select a folder. You should select "root folder" Select "root folder"
  3. Open versions folder Double-click versions folder
  4. Find the version you want to use specific JVM
    tip

    You may want to clone this version

  5. Open the version json file with any text editor (e.g. Notepad++)
    note

    You should not use any office suite!

  6. Find javaVersion block
  7. Change component field value with chosen one:
    note

    This list may be incomplete. You can view all available JVM versions here.

    • jre-legacy for Java 8
    • java-runtime-alpha for Java 16
    • java-runtime-beta and java-runtime-gamma for Java 17
    • java-runtime-delta for Java 21
    • java-runtime-epsilon for Java 25
  8. Save json file and restart the launcher. The version should now use selected Java version.
    note

    "Force update" checkbox will revert this change back to normal.