[BUG] Illegal Instruction in 2.1.77

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?

After auto updating claude code to 2.1.77 today it crashes on startup due to an illegal instruction execution.

This is similar but not the same as #35289 #24456 and other such reports

The issue happens only on 2.1.77, it works on 2.1.76 (validated with installing specific versions)

What Should Happen?

Claude code should start.

Error Messages/Logs

claude@claude:~$ curl -fsSL https://claude.ai/install.sh > claude_install.sh
claude@claude:~$ chmod +x claude_install.sh
claude@claude:~$ ./claude_install.sh 2.1.76
Setting up Claude Code...

✔ Claude Code successfully installed!

  Version: 2.1.76

  Location: ~/.local/bin/claude


  Next: Run claude --help to get started

✅ Installation complete!

claude@claude:~$ claude
 ▐▛███▜▌   Claude Code v2.1.76
▝▜█████▛▘  Sonnet 4.6 with medium effort · Claude Pro
  ▘▘ ▝▝    ~
claude@claude:~$ ./claude_install.sh 2.1.77
Setting up Claude Code...

✔ Claude Code successfully installed!

  Version: 2.1.77

  Location: ~/.local/bin/claude


  Next: Run claude --help to get started

✅ Installation complete!

claude@claude:~$ claude --help
============================================================
Bun v1.3.11 (a2743b6d) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
CPU: sse42 popcnt avx avx2
Args: "claude" "--help"
Features: jsc standalone_executable
Builtins: "bun:main"
Elapsed: 126ms | User: 49ms | Sys: 79ms
RSS: 1.24GB | Peak: 0.19GB | Commit: 1.24GB | Faults: 0 | Machine: 12.54GB

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_1a2743b6EggggC4w/u+E+ypRk8wx4Fimsx4Fopy14Fwoy8gFq368/Fmrs1zFgjo+yE694gzE+k3o8F_iznxuEmsxpuEu52n8F4iqjhG87i54Eu150hDy460hDmgrzhDA2AA

Illegal instruction (core dumped)


Executing host is a VM (only used by/for claude code) on a host-CPU-passthrough of a [i3-8100T](https://www.intel.de/content/www/de/de/products/sku/129944/intel-core-i38100t-processor-6m-cache-3-10-ghz/specifications.html) CPU which supports SSE4.1, SSE4.2, AVX2, which is correctly recognized by the ubuntu 24.04 the VM is running.

claude@claude:~$ lscpu
Architecture:                x86_64
  CPU op-mode(s):            32-bit, 64-bit
  Address sizes:             39 bits physical, 48 bits virtual
  Byte Order:                Little Endian
CPU(s):                      3
  On-line CPU(s) list:       0-2
Vendor ID:                   GenuineIntel
  Model name:                Intel(R) Core(TM) i3-8100T CPU @ 3.10GHz
    CPU family:              6
    Model:                   158
    Thread(s) per core:      1
    Core(s) per socket:      3
    Socket(s):               1
    Stepping:                11
    BogoMIPS:                6191.99
    Flags:                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon
                              rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f1
                             6c rdrand hypervisor lahf_lm abm 3dnowprefetch cpuid_fault pti ssbd ibrs ibpb stibp tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep
                              bmi2 erms invpcid mpx rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 xsaves arat vnmi umip md_clear flush_l1d arch_capabilities
Virtualization features:
  Virtualization:            VT-x
  Hypervisor vendor:         KVM
  Virtualization type:       full
Caches (sum of all):
  L1d:                       96 KiB (3 instances)
  L1i:                       96 KiB (3 instances)
  L2:                        12 MiB (3 instances)
  L3:                        16 MiB (1 instance)
NUMA:
  NUMA node(s):              1
  NUMA node0 CPU(s):         0-2
Vulnerabilities:
  Gather data sampling:      Unknown: Dependent on hypervisor status
  Indirect target selection: Not affected
  Itlb multihit:             Not affected
  L1tf:                      Mitigation; PTE Inversion; VMX flush not necessary, SMT disabled
  Mds:                       Mitigation; Clear CPU buffers; SMT Host state unknown
  Meltdown:                  Mitigation; PTI
  Mmio stale data:           Mitigation; Clear CPU buffers; SMT Host state unknown
  Reg file data sampling:    Not affected
  Retbleed:                  Mitigation; IBRS
  Spec rstack overflow:      Not affected
  Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
  Spectre v1:                Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Spectre v2:                Mitigation; IBRS; IBPB conditional; STIBP disabled; RSB filling; PBRSB-eIBRS Not affected; BHI SW loop, KVM SW loop
  Srbds:                     Unknown: Dependent on hypervisor status
  Tsa:                       Not affected
  Tsx async abort:           Not affected
  Vmscape:                   Not affected

Steps to Reproduce

I have no idea, sorry. Get a 8 year old low end CPU and run your software on it?

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.76

Claude Code Version

2.1.77

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Windows Terminal

Additional Information

_No response_