Minecraft Launcher starts internal CEF Chromium instead of Electron UI (Race Condition)

When starting the Minecraft Launcher on Linux by clicking the launcher icon repeatedly before the window becomes visible, the launcher enters a recovery/update state (“Updating…”). After this recovery finishes, clicking the launcher icon again launches the internal CEF Chromium browser instead of the normal Electron‑based launcher UI.

This Chromium instance is fully functional and exposes internal Chrome pages:

• chrome://flags

• chrome://gpu

• chrome://extensions

• chrome://history

• chrome://downloads

• chrome://privacy-sandbox-internals

The browser uses a persistent profile located at: ~/.minecraft/webcache2/Default

Observed Chromium version:

• CEF: 127.3.5+g114ea2a

• Chromium: 127.0.6533.120

Command line used by the fallback Chromium: /home/<user>/.minecraft/launcher/minecraft-launcher --no-sandbox --lang=en-US --log-file=/home/<user>/.minecraft/launcher_cef_log.txt --log-severity=info --disable-pinch --use-mock-keychain --disable-gpu-shader-disk-cache --autoplay-policy=no-user-gesture-required --use-fake-device-for-media-stream --flag-switches-begin --flag-switches-end

Expected behavior: Launcher should open the normal Electron UI and never expose the internal Chromium fallback browser.

Actual behavior: Launcher opens a fully functional Chromium browser instead of the launcher UI.

Reproduction steps:

1. Start Minecraft Launcher on Linux.

2. Before the window appears, click the launcher icon rapidly (10–20 times).

3. “Updating…” recovery window appears.

4. After recovery finishes, click the launcher icon again.

5. Chromium opens instead of the launcher.

Impact:

• Launcher UI does not load

• Chromium fallback is exposed

• Persistent Chrome profile created

• Potential security implications (Chrome sandbox disabled)

• Unexpected behavior for users

System:

• Linux Mint 23 (Cinnamon)

• No system Chromium installed

• Minecraft Launcher version: (v.3.36.2-2.6.2) (.deb)

  NOTE: This behavior may require repeating the steps multiple times due to a race condition.