Launcher problems

HMCL Launcher Error: SAXParseException in Log4jHandler

What the log looks like

org\.xml\.sax\.SAXParseException;[^\r\n]*(?:\r?\n)+\s*at org\.jackhuang\.hmcl\.util\.Log4jHandler\.run
org\.xml\.sax\.SAXParseException;[^\r\n]*log4j_(?:Throwable|Message)

How to fix it

  1. Update Hello Minecraft! Launcher (HMCL) to version 3.x (or at least 2.7.8.45+) from the official HMCL website or GitHub releases, where the faulty Log4j XML parser was removed.
  2. If Minecraft continues running normally after the popup appears, you can safely close the launcher error dialog until you update HMCL.
  3. If Minecraft also closes with a non-zero exit code, open your .minecraft/logs/latest.log or .minecraft/crash-reports/ folder directly to find the actual mod or Forge error that HMCL failed to display.
LoadersVanilla, Forge
SeverityBreaks something
CategoryLauncher problems

Check your own log

Related errors

Launcher problemsATLauncher Startup Crash: ChunkyException NullPointerException in makeStyleSheetClose any running ATLauncher or Java processes in Task Manager.Launcher problemsClassNotFoundException: net.fabricmc.loader.impl.launch.knot.KnotClientConnect to the internet and launch the profile once in online mode so your launcher can download any missing FLauncher problemsClassNotFoundException: net.minecraft.client.main.MainThe version jar in .minecraft/versions is missing or emptyLauncher problemsFabric Crash: Could Not Create Directory (iris-reserved)Switch away from the broken standalone Iris profile by installing standard Fabric Loader for your Minecraft veLauncher problemsFabric: Minecraft game provider couldn't locate the game!Run the vanilla (unmodded) profile for that exact Minecraft version once in your launcher so it downloads a clLauncher problemsForge Crashes on Startup: Missing TByteObjectHashMap (trove4j Library)Use the official Minecraft Launcher or an established third-party launcher (such as Prism Launcher or MultiMC)