portable-ruby SIGABRT in SystemCommand#exec3 child during cask upgradeCask

[shaanmajid]

Output of brew config

Your system is ready to brew.

Output of brew doctor

HOMEBREW_VERSION: 6.0.4-2-g134f795
ORIGIN: https://github.com/Homebrew/brew
HEAD: 134f795204c20533ba78496da2fa67ee23d08a65
Last commit: 6 hours ago
Branch: main
Core tap: N/A
Core cask tap: N/A
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DOWNLOAD_CONCURRENCY: 20
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 10
HOMEBREW_NO_COLOR: set
HOMEBREW_REQUIRE_TAP_TRUST: set
Homebrew Ruby: 4.0.5 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.5_1/bin/ruby
CPU: deca-core 64-bit arm_blizzard_avalanche
Clang: 21.0.0 build 2100
Git: 2.54.0 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.5.1-arm64
CLT: 26.5.0.0.1777544298
Xcode: 26.5
Metal Toolchain: N/A
Rosetta 2: false

Description of issue

I was running a normal brew upgrade to update installed formulae and casks. The upgrade included visual-studio-code, whose cask has uninstall launchctl: "com.microsoft.VSCode.ShipIt", quit: "com.microsoft.VSCode". I had left the command sitting at the password prompt for a while before entering the password; I do not know whether that timing is relevant.

Homebrew's bundled portable Ruby aborted during the cask upgrade path; notably, the overall upgrade continued and completed successfully. The macOS crash report says the Ruby process "crashed on child side of fork pre-exec", and the stack lines up with SystemCommand#exec3 forking and then calling exec(...).

Relevant code path in the installed Homebrew checkout:

• Library/Homebrew/system_command.rb:407 forks in SystemCommand#exec3
• Library/Homebrew/system_command.rb:414 calls exec(...)
• Library/Homebrew/cask/artifact/abstract_uninstall.rb:221 runs uninstall_quit
• Library/Homebrew/cask/artifact/abstract_uninstall.rb:272 calls osascript via system_command from running?

Terminal excerpt around the crash

==> Upgrading visual-studio-code
  1.125.1 -> 1.126.0
==> Removing launchctl service com.microsoft.VSCode.ShipIt
Password:
==> Quitting application 'com.microsoft.VSCode'...
ruby(81060,0x1f88f1e80) malloc: tiny_free_list_remove_ptr: Internal invariant broken (prev ptr of next): ptr=0x11fa70fe0, next_prev=0x11c61e390
ruby(81060,0x1f88f1e80) malloc: *** set a breakpoint in malloc_error_break to debug
/opt/homebrew/Library/Homebrew/system_command.rb:414: [BUG] Aborted at 0x000000018c7365e8
ruby 4.0.5 (2026-05-20 revision 64336ffd0e) +PRISM [arm64-darwin20]

-- Ruby level backtrace information ----------------------------------------
/opt/homebrew/Library/Homebrew/brew.rb:121:in '<main>'
/opt/homebrew/Library/Homebrew/cmd/upgrade.rb:306:in 'run'
/opt/homebrew/Library/Homebrew/cmd/upgrade.rb:830:in 'upgrade_outdated_casks!'
/opt/homebrew/Library/Homebrew/cask/upgrade.rb:259:in 'upgrade_casks!'
/opt/homebrew/Library/Homebrew/cask/upgrade.rb:259:in 'each_with_index'
/opt/homebrew/Library/Homebrew/cask/upgrade.rb:259:in 'each'
/opt/homebrew/Library/Homebrew/cask/upgrade.rb:260:in 'block in upgrade_casks!'
/opt/homebrew/Library/Homebrew/cask/upgrade.rb:417:in 'upgrade_cask'
/opt/homebrew/Library/Homebrew/cask/installer.rb:603:in 'start_upgrade'
/opt/homebrew/Library/Homebrew/cask/installer.rb:657:in 'uninstall_artifacts'
/opt/homebrew/Library/Homebrew/cask/artifact_set.rb:15:in 'each'
/opt/homebrew/Library/Homebrew/cask/artifact_set.rb:15:in 'each'
/opt/homebrew/Library/Homebrew/cask/installer.rb:687:in 'block in uninstall_artifacts'
/opt/homebrew/Library/Homebrew/cask/artifact/uninstall.rb:46:in 'uninstall_phase'
/opt/homebrew/Library/Homebrew/cask/artifact/uninstall.rb:46:in 'each'
/opt/homebrew/Library/Homebrew/cask/artifact/uninstall.rb:47:in 'block in uninstall_phase'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:94:in 'dispatch_uninstall_directive'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:222:in 'uninstall_quit'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:222:in 'each'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:234:in 'block in uninstall_quit'
/opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.5_1/lib/ruby/4.0.0/timeout.rb:306:in 'timeout'
/opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.5_1/lib/ruby/4.0.0/timeout.rb:38:in 'handle_timeout'
/opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.5_1/lib/ruby/4.0.0/timeout.rb:296:in 'block in timeout'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:235:in 'block (2 levels) in uninstall_quit'
<internal:kernel>:169:in 'loop'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:238:in 'block (3 levels) in uninstall_quit'
/opt/homebrew/Library/Homebrew/cask/artifact/abstract_uninstall.rb:272:in 'running?'
/opt/homebrew/Library/Homebrew/system_command.rb:46:in 'system_command'
/opt/homebrew/Library/Homebrew/system_command.rb:106:in 'run'
/opt/homebrew/Library/Homebrew/system_command.rb:143:in 'run!'
/opt/homebrew/Library/Homebrew/system_command.rb:348:in 'each_output_line'
/opt/homebrew/Library/Homebrew/system_command.rb:407:in 'exec3'
/opt/homebrew/Library/Homebrew/system_command.rb:407:in 'fork'
/opt/homebrew/Library/Homebrew/system_command.rb:414:in 'block in exec3'
/opt/homebrew/Library/Homebrew/system_command.rb:414:in 'exec'

Crash report excerpt from ruby-2026-06-25-135826.ips

Process: ruby
Path: /opt/homebrew/*/ruby
Parent Process: ruby
Responsible Process: ghostty
Exception Type: EXC_CRASH (SIGABRT)
Termination Reason: Abort trap: 6
Application Specific Information:
crashed on child side of fork pre-exec

Thread 0 Crashed:
__pthread_kill
pthread_kill
raise
rb_bug_for_fatal_signal
sigabrt
_sigtramp
pthread_kill
abort
malloc_vreport
malloc_zone_error
tiny_free_list_remove_ptr
tiny_free_detach_region
tiny_malloc_should_clear
szone_malloc_should_clear
szone_realloc
_malloc_zone_realloc
_realloc
rb_gc_impl_realloc
ruby_sized_xrealloc2
str_buf_cat4
fill_envp_buf_i
st_general_foreach
rb_st_foreach
rb_execarg_parent_start1
rb_protect
rb_f_exec
f_exec
...
rb_f_fork
...

Upgrade completed after the crash output

Application 'com.microsoft.VSCode' quit successfully.
==> Backing App 'Visual Studio Code.app' up to '/opt/homebrew/Caskroom/visual-studio-code/1.125.1/Visual Studio Code.app'
==> Removing App '/Applications/Visual Studio Code.app'
==> Unlinking Binary '/opt/homebrew/bin/code'
==> Unlinking Binary '/opt/homebrew/bin/code-tunnel'
==> Moving App 'Visual Studio Code.app' to '/Applications/Visual Studio Code.app'
==> Linking Binary 'code' to '/opt/homebrew/bin/code'
==> Linking Binary 'code-tunnel' to '/opt/homebrew/bin/code-tunnel'
==> Purging files for version 1.125.1 of Cask visual-studio-code
🍺  visual-studio-code was successfully upgraded!
==> Reopening 1 application closed during upgrade:
com.microsoft.VSCode
==> Upgraded 12 outdated packages
usage               3.5.2          -> 3.5.3
mise                2026.6.11      -> 2026.6.14
cryptography        48.0.1         -> 49.0.0
just                1.53.0         -> 1.54.0
uv                  0.11.23        -> 0.11.24
luajit              2.1.1781602682 -> 2.1.1782381659
node                26.3.1         -> 26.4.0
codex               0.142.0        -> 0.142.2
firefox             152.0.1        -> 152.0.3
rustdesk            1.4.7          -> 1.4.8
signal              8.15.0         -> 8.16.0
visual-studio-code  1.125.1        -> 1.126.0

Local analysis

This appears more like a portable Ruby / macOS allocator abort during Homebrew's SystemCommand#exec3 fork/exec path than a VS Code application crash. The crash report says the child crashed before exec completed, and the native stack is in Ruby's exec argument/environment preparation (fill_envp_buf_i, rb_execarg_parent_start1, rb_f_exec) after a malloc invariant failure (tiny_free_list_remove_ptr).

Relevant casks

visual-studio-code

[p-linnane]

Thanks for the report. This should be fixed by Homebrew/brew#22880.

[shaanmajid]

Thank you for the quick fix!