[BUG] Claude Code v2.1.77 crashes with "Illegal instruction" on RHEL 8 (x86_64)

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?

Description

Claude Code v2.1.77 crashes immediately on startup with a segmentation fault / "Illegal instruction" on RHEL 8.10 (x86_64). Even claude --version triggers the crash. Versions 2.1.75 and 2.1.76 work correctly on the same machine.

Reproduction steps

1. Install Claude Code v2.1.77 on RHEL 8.10 (x86_64)
2. Run any claude command:

``
claude --version
claude --resume
``

1. Observe crash

Crash output

$ claude --resume
============================================================
Bun v1.3.11 (a2743b6d) Linux x64 (baseline)
Linux Kernel v4.18.0 | glibc v2.28
CPU: sse42 popcnt avx avx2
Args: "claude" "--resume"
Elapsed: 2ms | User: 0ms | Sys: 1ms
RSS: 33.56MB | Peak: 8.99MB | Commit: 33.56MB | Faults: 0

panic(main thread): Segmentation fault at address 0x0
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

 https://bun.report/1.3.11/B_1a2743b6AA+izT2l8g6Cojog6Com0O6ylg6CA2AA

Illegal instruction (core dumped)

Bisection

| Version | Binary size | Status |
|---------|------------|--------|
| 2.1.75 | 235,274,982 bytes | Works (claude --version returns 2.1.75) |
| 2.1.76 | 235,555,347 bytes | Works (claude --version returns 2.1.76) |
| 2.1.77 | 235,864,091 bytes | Crashes (Illegal instruction / segfault) |

All three binaries report the same embedded Bun version string (Bun v1.3.11), but the v2.1.77 binary is ~300KB larger than v2.1.76, suggesting a change in the Bun build or bundled JS payload.

Environment

• OS: Red Hat Enterprise Linux 8.10 (Ootpa)
• Kernel: 4.18.0-553.111.1.el8_10.x86_64
• glibc: 2.28
• CPU: Intel Xeon Gold 6240 @ 2.60GHz
• CPU flags: sse, sse2, sse4_1, sse4_2, popcnt, avx, avx2
• Node.js: v24.14.0
• Claude Code install: standalone binary via ~/.local/share/claude/versions/
• Binary type: ELF 64-bit LSB executable, x86-64, dynamically linked

Workaround

Symlinking back to v2.1.76 restores functionality:

ln -sf /users/$USER/.local/share/claude/versions/2.1.76 /users/$USER/.local/bin/claude

Analysis

The crash is a null-pointer segfault (address 0x0) in the main thread before any user code runs, suggesting an issue in the Bun runtime initialization. Since the Bun version string is the same across all three builds, the Bun binary embedded in v2.1.77 may have been com
piled with different flags or linked against a newer glibc. RHEL 8's glibc 2.28 and kernel 4.18 are both relatively old but still within the "baseline" tier that Bun claims to support.

This may be related to upstream Bun issue or a change in how Claude Code's standalone binary is built.

Bun crash report link

https://bun.report/1.3.11/B_1a2743b6AA+izT2l8g6Cojog6Com0O6ylg6CA2AA

What Should Happen?

Claude should start up

Error Messages/Logs

Bun v1.3.11 (a2743b6d) Linux x64 (baseline)
Linux Kernel v4.18.0 | glibc v2.28
CPU: sse42 popcnt avx avx2
Args: "claude" "--resume"
Elapsed: 2ms | User: 0ms | Sys: 1ms
RSS: 33.56MB | Peak: 8.99MB | Commit: 33.56MB | Faults: 0

panic(main thread): Segmentation fault at address 0x0
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

To send a redacted crash report to Bun's team,
please file a GitHub issue using the link below:

 https://bun.report/1.3.11/B_1a2743b6AA+izT2l8g6Cojog6Com0O6ylg6CA2AA

Illegal instruction (core dumped)

Steps to Reproduce

1. Install Claude Code v2.1.77 on RHEL 8.10 (x86_64)
2. Run any claude command:

``
claude --version
claude --resume
``

1. Observe crash

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.76

Claude Code Version

2.1.77

Platform

AWS Bedrock

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_