Claude Desktop crashes on macOS Tahoe 26.3.1 — Crashpad mach_port_request_notification failure

Summary

Claude Desktop (v1.1.7714) crashes repeatedly on macOS Tahoe 26.3.1. Started the week of March 12, 2026. Same hardware/OS configuration works fine on a second machine.

Environment

• macOS: Tahoe 26.3.1, Build 25D771280a
• Hardware: Apple M4 Pro, 24GB RAM (Mac16,7)
• Claude Desktop: v1.1.7714, Electron 40.4.1
• Installed via: Homebrew Cask

Root Cause

Crashpad (chrome_crashpad_handler) fails on mach_port_request_notification with KERN_INVALID_CAPABILITY (error 20). This error fires every ~1 second and eventually kills the main Electron process.

Exact error (repeats every second):

[FATAL:third_party/crashpad/crashpad/handler/mac/exception_handler_server.cc:76]
Check failed: kr == KERN_SUCCESS. mach_port_request_notification: (os/kern) invalid capability (20)

Crash report exception:

"exception": {
  "codes": "0x0000000000000001, 0x00000001004e7380",
  "type": "EXC_BREAKPOINT",
  "signal": "SIGTRAP"
}

Behavior

• App launches, shows login screen briefly, then crashes (15-30 seconds)
• Crashes whether logged in or not
• When crashpad binary is physically removed, app survives much longer (2+ minutes, completed login and Co-Work session), confirming crashpad as the cause
• However, modifying the binary breaks code signature → "invalid installation" error, so this is not a viable user workaround

What Was Tried (all failed to resolve)

1. Full uninstall/reinstall via brew reinstall --cask claude (multiple times)
2. Complete deletion of ~/Library/Application Support/Claude/
3. Deleting Cookies, Preferences, Keychain entries (Claude Safe Storage)
4. tccutil reset All com.anthropic.claudefordesktop
5. Removing quarantine: xattr -cr /Applications/Claude.app
6. Launch flags: --disable-gpu, --disable-crash-reporter, --password-store=basic, --disable-breakpad
7. Environment variables: ELECTRON_DISABLE_CRASH_REPORTER=1

Suggested Fix

Update Crashpad to handle KERN_INVALID_CAPABILITY gracefully on macOS Tahoe, or add error recovery so the FATAL assertion doesn't propagate to the main process.

Diagnostic Evidence

• 79 crash reports in ~/Library/Logs/DiagnosticReports/chrome_crashpad_handler-*.ips
• Full stderr capture showing the FATAL loop available on request