Launcher problems

HMCL Crash When Adjusting Download Concurrency Slider

What the log looks like

java\.lang\.IllegalArgumentException\s+at [^\n]*ThreadPoolExecutor\.setCorePoolSize[^\n]*\s+at org\.jackhuang\.hmcl\.task\.FetchTask\.setDownloadExecutorConcurrency
org\.jackhuang\.hmcl\.task\.FetchTask\.setDownloadExecutorConcurrency\(FetchTask\.java:\d+\)

How to fix it

  1. Update HMCL to a version newer than 3.5.5.235 via the launcher's built-in update page or by downloading the latest release from the official HMCL website, as the developers have already patched this bug.
  2. If you cannot update right away, restart HMCL to clear the error state and keep 'Auto choose concurrency' enabled in the Download settings instead of dragging the slider manually.
  3. If you must set a custom thread count on HMCL 3.5.5, close the launcher first and edit the concurrency value directly inside your hmcl.json configuration file rather than using the UI slider.
LoadersVanilla, Forge, Neoforge, Fabric, Quilt
SeverityBreaks something
CategoryLauncher problems

Check your own log

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