Cowork crashes with EXC_BAD_INSTRUCTION (SIGILL) on Mac Pro 5,1 (x86-64, no AVX) — Claude Code v2.1.170

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

• Hardware: Mac Pro 5,1 (2010), Intel X86-64, no AVX support
• macOS: 14.6.1 (23G93)
• Claude Desktop: 2.1.170
• Bug type: 309, EXC_BAD_INSTRUCTION / SIGILL
• Crash at: dyld runAllInitializersForMain()
• Claude Code process exits with code 132 immediately on session start
• Incident: BBB9BE2D-753E-411D-8119-A58438E73D87

Binary fails to initialize — crash happens before any user code runs.
Likely cause: build target raised to require AVX or newer instruction set
not present on Westmere/Nehalem CPUs (Mac Pro 5,1).

What Should Happen?

Expected fix:
Please compile Claude Code with a lower CPU target baseline
(no AVX requirement) to support Intel Westmere/Nehalem processors.
These CPUs run macOS Sonoma 14 officially (with OpenCore) and should
be supported. A universal x86-64 build without AVX minimum would
resolve this.

Alternatively: document the minimum CPU requirements clearly so
users know before installing.

claude-2026-06-11-142523.ips.zip

Error Messages/Logs

Error Logs:

1. main.log:
Claude Code process exited with code 132
error_category: process_crashed
unhealthy_reason: system_error
had_first_response: false
seconds_to_outcome: 0

2. Diagnostic Report (~/Library/Logs/DiagnosticReports/claude-2026-06-11-142523.ips):
exception: EXC_BAD_INSTRUCTION / SIGILL
termination: "Illegal instruction: 4"
faultingThread: 0 (com.apple.main-thread)
crash at: dyld4::APIs::runAllInitializersForMain()
cpuType: X86-64
modelCode: MacPro5,1
bundleID: com.anthropic.claude-code
version: 2.1.170
incident_id: BBB9BE2D-753E-411D-8119-A58438E73D87

3. Crash happens at dyld initialization — before any user code runs.
   Binary exits immediately, no session starts, no response received.

Steps to Reproduce

1. Hardware: Mac Pro 5,1 (2010), Intel X86-64 (no AVX support)
2. macOS 14.6.1 (23G93) — running via OpenCore
3. Install Claude Desktop 2.1.170
4. Open Claude Desktop → navigate to Cowork tab
5. Create a new project/space with any folder
6. Enter any instruction/prompt
7. → Claude Code process exits immediately with code 132 (SIGILL)

Reproduced: every single time, 100% reproducible
Fresh install: confirmed (app deleted, cache cleared, reinstalled — same result)
Other Claude features: work normally (claude.ai chat, etc.)
Only Cowork / local agent mode affected

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.11847.5 (9692f0) 2026-06-09T17:34:27.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_