Launcher problems

HMCL Fails to Install Minecraft (JsonSyntaxException: duplicate key: null)

What it looks like in the log

com.google.gson.JsonSyntaxException: duplicate key: null

How to fix it

  1. Update HMCL to version 3.2.136 or newer using the built-in update button in Launcher Settings, or download the latest official JAR/EXE directly from hmcl.huangyuhui.net.
  2. If you installed HMCL via a Linux distribution repository (such as Manjaro, Arch, or Deepin), remove the outdated snapshot package and install an up-to-date package (such as hmcl-bin or hmcl-git) or launch the official HMCL JAR directly with Java.
  3. Open HMCL's Download settings, ensure a working download source (Official or BMCLAPI) is selected, and retry installing the Minecraft version.
LoadersVanilla
SeverityBreaks something
CategoryLauncher problems

Check your own log

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