# Minecraft Launcher: every unzip.mojom.Unzipper / patch.mojom.FilePatcher subprocess aborts with uncaught std::bad_function_call

## What happens

The launcher UI runs fine, but every Chromium *utility* subprocess of sub-type
`unzip.mojom.Unzipper` or `patch.mojom.FilePatcher` aborts immediately on startup
with SIGABRT. Other utility sub-types (renderer, gpu, network.mojom.NetworkService,
storage.mojom.StorageService, audio.mojom.AudioService) start normally and never crash.

Consequence: the services that unpack and patch downloaded game files never run, so
game installs/updates that depend on them fail or stall.

## Expected

Unzipper/FilePatcher subprocesses start and complete normally.

## Evidence

Cause, confirmed by recovering the in-flight exception object from the core dump:
an **uncaught `std::bad_function_call`** — an empty `std::function` invoked with no
matching handler anywhere on the stack, so unwinding runs off the end and terminates.

    typeinfo for std::bad_function_call   (resolved from __cxa_exception header)

Symbolized stack (Arch debuginfod; liblauncher.so ships no debug symbols, so its
frames stay unresolved — not guessed):

    #0  __pthread_kill_implementation
    #2  __GI_raise
    #3  __GI_abort
    #4  __gnu_cxx::__verbose_terminate_handler ()
    #5  __cxxabiv1::__terminate ()
    #6  __cxa_call_terminate (ue_header_in=0x55fcf1792d50)
    #7  __cxxabiv1::__gxx_personality_v0 (actions=6, ...)
    #8  _Unwind_RaiseException_Phase2
    #9  _Unwind_Resume
    #10 ?? () from ~/.minecraft/launcher/liblauncher.so   (+0x1360a3)
    #11 ?? () from ~/.minecraft/launcher/liblauncher.so   (+0x29f2f1)
    ...
    #14 RunLauncher () from ~/.minecraft/launcher/liblauncher.so

All other threads are idle CEF workers parked in pthread_cond_wait; nothing else in flight.

## Reproduction / correlation

The launcher's own log spawn lines match the coredumps 1:1, every single time
(log timestamps UTC, coredumps IDT = UTC+3):

| Log spawns (UTC)                          | Coredumps (IDT)        |
|-------------------------------------------|------------------------|
| 15 x Unzipper, 2026-09-10 05:40:55-59      | 15 aborts, 08:40:55-59 |
| 1 x Unzipper, 2026-09-10 10:40:56          | 1 abort, 13:40:56      |
| 1 x Unzipper, 2026-09-10 15:40:55          | 1 abort, 18:40:55      |
| 1 x Unzipper, 2026-09-10 20:40:55          | 1 abort, 23:40:55      |
| FilePatcher + Unzipper, 2026-09-11 12:27:21| 2 aborts, 15:27:21     |

The ~5-hourly cadence is the launcher's periodic update check. 100% failure rate for
these two sub-types since install; 0% for all others.

Example log line immediately preceding a crash:

    [Info: 2026-09-11 12:27:21.193741505: LauncherAppBrowser.cpp(82)] Will launch a
    Chromium subprocess with command line string: /proc/self/exe --type=utility
    --utility-sub-type=patch.mojom.FilePatcher --lang=en-US --service-sandbox-type=service
    --no-sandbox ...

Crashed processes inherit the zygote's argv, so coredumpctl reports them as
`--type=zygote`; the sub-type is only visible in the launcher log.

## Ruled out

- Not OOM: 62 GB RAM, 33 GB available, 122 GB swap free, no OOM kills in journal.
- Not disk: 39% used.
- Not a system update: package installed 2026-09-10 08:35, first crash burst 08:40,
  five minutes later. Present since install.
- Not resource/config drift: reproduces on every attempt across two days and a reboot.

## System

- Omarchy 4.0.3-1, Linux 7.2.3-arch1-3, Hyprland (Wayland)
- minecraft-launcher 1:2.1.3-3 (repo: omarchy, pkgs.omarchy.org/stable)
- The aborting binary is NOT the packaged one: it is Mojang's self-downloaded
  ~/.minecraft/launcher/liblauncher.so (written 2026-09-10 08:39), bundled CEF.

## Note on scope

The faulting code is in Mojang's proprietary liblauncher.so, which is identical on
every distribution. I have not verified this is Omarchy-specific — it has not been
compared against vanilla Arch or another distro. Unless it can be shown to reproduce
only under Omarchy, this is most likely an upstream Mojang bug and belongs at
https://bugs.mojang.com under the Minecraft Launcher project.

## Separate, possibly related

The Omarchy-packaged bootstrap /usr/bin/minecraft-launcher also took a SIGSEGV
(SEGV_MAPERR, null instruction pointer at frame #0) on 2026-09-10 08:35:48, during
GTK3 key-event dispatch:

    #0  0x0000000000000000
    #1  g_signal_emit_valist (libgobject-2.0.so.0)
    #3  ?? (libgtk-3.so.0 + 0xbad66)
    #9  gtk_window_propagate_key_event (libgtk-3.so.0)
    #17 gtk_main_do_event (libgtk-3.so.0)

Also a null callback, but a different binary and a different trigger. Not investigated further.

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Filed by Claude Opus 5 (1M context) via Claude Code.