[BUG] Bun segfault/SIGABRT on startup — Ubuntu 26.04.1 LTS (glibc 2.43)

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?

Claude Code crashes on every startup attempt (both VSCode extension and
CLI installed via npm) with SIGSEGV or SIGABRT from Bun, before doing
anything. Crash is intermittent in exact signal/address but happens
almost every time.

What Should Happen?

Claude Code should start normally without crashing.

Error Messages/Logs

panic(main thread): Segmentation fault at address 0x5
oh no: Bun has crashed.
https://bun.report/1.4.3/l_1047f2e8mggggQugogC2qqm5Dms3k5Ds8rmsE6jn7tC45x5tC_4y4s5Di92s5Dms3k5Dw9q12Ei/j02E6+jl8Em717+E4hxumC_mz/s5Dms3k5Ds8rmsEkni7yE+9n6kCA2AK

---

panic(main thread): abort() called
oh no: Bun has crashed.
https://bun.report/1.4.3/l_1047f2e8kggggQugggC26wpB63tR2ukKwm+ijCwl+ijCmomyzEimyhyEuwvyzE6pohyE46o02Eq8u52Emkw52Euw4nlC_i92s5Di92s5D_i92s5Dms3k5D0k7msEAa

---

panic(main thread): abort() called
oh no: Bun has crashed.
https://bun.report/1.4.3/l_1047f2e8kggggQkgggC26wpB63tR2ukKwm+ijCwl+ijCmomyzEimyhyEi8xhyEuwvyzE6pohyEg2v12Eun8z2E6+jl8Em717+Eiwn6kC2kkl8Em717+Eq1wtlCm+ly/C4i9x/CAa

Steps to Reproduce

1. Fresh install of Ubuntu 26.04.1 LTS (kernel 7.0.0-31-generic, glibc 2.43)
2. Install Claude Code via VSCode extension (v2.1.270) or via:

sudo npm install -g @anthropic-ai/claude-code

1. Run claude in terminal, or open Claude Code panel in VSCode
2. Bun crashes with SIGSEGV or SIGABRT before any output/interaction
3. Behavior is intermittent — occasionally starts, usually crashes
4. Also reproduced inside a fresh Ubuntu 24.04 Docker container running

on the same host — same crash occurs

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.270 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

• Bun version: 1.4.3
• Reproduced both via VSCode extension and standalone CLI (npm install)
• Reproduced inside Docker container (ubuntu:24.04) running on the same

host, suggesting the issue may relate to host kernel (7.0.0) rather
than purely glibc version in the container

• SMART health check on system disk: PASSED, no errors
• Basic RAM test (memtester, 1 pass, 2GB): no errors found
• This appears to be a very fresh combination (Ubuntu 26.04.1, glibc 2.43,

kernel 7.0.0) that may not yet be tested against Bun 1.4.3