[BUG] Crash C000001D (ILLEGAL_INSTRUCTION) running claude.exe — request for AVX-free build

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?

Crash C000001D (ILLEGAL_INSTRUCTION) running claude.exe — request for AVX-free build

Hello Anthropic team,

I am reporting an immediate crash when launching the native binary included with the Claude Code extension. Below are the key technical details:

• Behavior: The process exits immediately with an unhandled exception: C000001D (ILLEGAL_INSTRUCTION).
• Environment: Windows; the executable is signed and the Authenticode signature verifies as valid. Static dependency checks with Dependencies show no missing DLLs.
• Diagnostic artifact: I captured a ProcDump at the time of the crash: claude.exe_260427_171257.dmp (available for analysis).
• Hardware: Intel Core2 Duo P7550 @ 2.26GHz. Coreinfo output indicates no AVX or AVX2 support; SSE4.2 is also absent.

Interpretation: The crash appears to be caused by the binary executing CPU instructions not supported by this older CPU (ILLEGAL_INSTRUCTION). This suggests the build requires modern SIMD instruction sets (AVX/AVX2 or similar).

Request

1. Please provide an alternative build of the native client compiled without AVX/AVX2 (a fallback build compatible with older CPUs).
2. Alternatively, confirm the minimum CPU instruction set requirements for the current release so I can plan appropriate hardware or VM usage.

I can provide the following artifacts for your analysis:

• ProcDump file: claude.exe_260427_171257.dmp
• Coreinfo output showing CPU feature flags
• SHA256 hash of the executable and the Dependencies log

Please indicate the preferred secure channel or ticketing method for uploading these artifacts.

Thank you for your help — I can supply any additional logs or steps you request.

Best regards,
Antônio

What Should Happen?

Crash C000001D (ILLEGAL_INSTRUCTION) running claude.exe — request for AVX-free build

Error Messages/Logs

Steps to Reproduce

<!-- Failed to upload "claude.exe_260427_171257.dmp" -->

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Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.120.0

Platform

Other

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

The dump file is too big