Launcher problems

HMCL Crash: UnknownFormatConversionException (Conversion = 'D')

What it looks like in the log

java.util.concurrent.CompletionException: java.util.UnknownFormatConversionException: Conversion = 'D'

How to fix it

  1. Update HMCL to version 3.5.3.230 or newer using the built-in launcher update button (switch to the development/preview channel if stable is still on 3.5.3.229) or download the latest release directly from the official HMCL GitHub Releases page.
  2. Replace your old HMCL.exe or HMCL.jar file with the newly downloaded version and launch it.
  3. Start Minecraft again; if the game itself was crashing, the updated HMCL crash analyzer will now open properly so you can read and fix the actual game error (or check the .minecraft/crash-reports folder directly).
LoadersVanilla, Forge, Neoforge, Fabric, Quilt
SeverityBreaks something
CategoryLauncher problems

Check your own log

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