[BUG] CPU without AVX → Bun crashes → SIGILL

[vsisnet]

Preflight Checklist

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

What's Wrong?

2026-02-10 08:36:16.278 [info] From claude: ============================================================
Bun Canary v1.3.9-canary.51 (d5628db2) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
Args: "/root/.vscode-server/extensions/anthropic.claude-code-2.1.38-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose"
2026-02-10 08:36:16.278 [info] From claude: "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "de"...
Features: jsc no_avx2 no_avx standalone_executable
Builtins: "bun:main"
Elapsed: 51376ms | User: 44033ms | Sys: 6948ms
RSS: 14.38GB | Peak: 5.22GB | Commit: 14.38GB | Faults: 181 | Machine: 16.78GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5BBB5800000

2026-02-10 08:36:16.279 [info] From claude: 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/1.3.9/B_2d5628dbEggggigD4skkwE+ypRgpjt9Cstg4pDkgt2pD+2+k1Di1jhmE0os1sEwj6vtF_6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhEA227ChgggwqC

2026-02-10 08:36:16.903 [info] From claude: curl: (22) The reque
2026-02-10 08:36:16.904 [info] From claude: sted URL returned error: 502

2026-02-10 08:36:17.206 [info] Closing Claude on channel: zda9d07oz4
2026-02-10 08:36:17.207 [error] Error from Claude (on channel zda9d07oz4): Error: Claude Code process terminated by signal SIGILL

What Should Happen?

2026-02-10 08:36:16.278 [info] From claude: ============================================================
Bun Canary v1.3.9-canary.51 (d5628db2) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
Args: "/root/.vscode-server/extensions/anthropic.claude-code-2.1.38-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose"
2026-02-10 08:36:16.278 [info] From claude: "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "de"...
Features: jsc no_avx2 no_avx standalone_executable
Builtins: "bun:main"
Elapsed: 51376ms | User: 44033ms | Sys: 6948ms
RSS: 14.38GB | Peak: 5.22GB | Commit: 14.38GB | Faults: 181 | Machine: 16.78GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5BBB5800000

2026-02-10 08:36:16.279 [info] From claude: 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/1.3.9/B_2d5628dbEggggigD4skkwE+ypRgpjt9Cstg4pDkgt2pD+2+k1Di1jhmE0os1sEwj6vtF_6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhEA227ChgggwqC

2026-02-10 08:36:16.903 [info] From claude: curl: (22) The reque
2026-02-10 08:36:16.904 [info] From claude: sted URL returned error: 502

2026-02-10 08:36:17.206 [info] Closing Claude on channel: zda9d07oz4
2026-02-10 08:36:17.207 [error] Error from Claude (on channel zda9d07oz4): Error: Claude Code process terminated by signal SIGILL

Error Messages/Logs

2026-02-10 08:36:16.278 [info] From claude: ============================================================
Bun Canary v1.3.9-canary.51 (d5628db2) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
Args: "/root/.vscode-server/extensions/anthropic.claude-code-2.1.38-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose" 
2026-02-10 08:36:16.278 [info] From claude: "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "de"...
Features: jsc no_avx2 no_avx standalone_executable 
Builtins: "bun:main" 
Elapsed: 51376ms | User: 44033ms | Sys: 6948ms
RSS: 14.38GB | Peak: 5.22GB | Commit: 14.38GB | Faults: 181 | Machine: 16.78GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5BBB5800000

2026-02-10 08:36:16.279 [info] From claude: 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/1.3.9/B_2d5628dbEggggigD4skkwE+ypRgpjt9Cstg4pDkgt2pD+2+k1Di1jhmE0os1sEwj6vtF_6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhEA227ChgggwqC


2026-02-10 08:36:16.903 [info] From claude: curl: (22) The reque
2026-02-10 08:36:16.904 [info] From claude: sted URL returned error: 502

2026-02-10 08:36:17.206 [info] Closing Claude on channel: zda9d07oz4
2026-02-10 08:36:17.207 [error] Error from Claude (on channel zda9d07oz4): Error: Claude Code process terminated by signal SIGILL

Steps to Reproduce

2026-02-10 08:36:16.278 [info] From claude: ============================================================
Bun Canary v1.3.9-canary.51 (d5628db2) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
Args: "/root/.vscode-server/extensions/anthropic.claude-code-2.1.38-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose"
2026-02-10 08:36:16.278 [info] From claude: "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "de"...
Features: jsc no_avx2 no_avx standalone_executable
Builtins: "bun:main"
Elapsed: 51376ms | User: 44033ms | Sys: 6948ms
RSS: 14.38GB | Peak: 5.22GB | Commit: 14.38GB | Faults: 181 | Machine: 16.78GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5BBB5800000

2026-02-10 08:36:16.279 [info] From claude: 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/1.3.9/B_2d5628dbEggggigD4skkwE+ypRgpjt9Cstg4pDkgt2pD+2+k1Di1jhmE0os1sEwj6vtF_6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhEA227ChgggwqC

2026-02-10 08:36:16.903 [info] From claude: curl: (22) The reque
2026-02-10 08:36:16.904 [info] From claude: sted URL returned error: 502

2026-02-10 08:36:17.206 [info] Closing Claude on channel: zda9d07oz4
2026-02-10 08:36:17.207 [error] Error from Claude (on channel zda9d07oz4): Error: Claude Code process terminated by signal SIGILL

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.34

Claude Code Version

2.1.38

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Terminal.app (macOS)

Additional Information

2026-02-10 08:36:16.278 [info] From claude: ============================================================
Bun Canary v1.3.9-canary.51 (d5628db2) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
Args: "/root/.vscode-server/extensions/anthropic.claude-code-2.1.38-linux-x64/resources/native-binary/claude" "--output-format" "stream-json" "--verbose"
2026-02-10 08:36:16.278 [info] From claude: "--input-format" "stream-json" "--max-thinking-tokens" "31999" "--model" "de"...
Features: jsc no_avx2 no_avx standalone_executable
Builtins: "bun:main"
Elapsed: 51376ms | User: 44033ms | Sys: 6948ms
RSS: 14.38GB | Peak: 5.22GB | Commit: 14.38GB | Faults: 181 | Machine: 16.78GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x5BBB5800000

2026-02-10 08:36:16.279 [info] From claude: 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/1.3.9/B_2d5628dbEggggigD4skkwE+ypRgpjt9Cstg4pDkgt2pD+2+k1Di1jhmE0os1sEwj6vtF_6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhE6muvhEA227ChgggwqC

2026-02-10 08:36:16.903 [info] From claude: curl: (22) The reque
2026-02-10 08:36:16.904 [info] From claude: sted URL returned error: 502

2026-02-10 08:36:17.206 [info] Closing Claude on channel: zda9d07oz4
2026-02-10 08:36:17.207 [error] Error from Claude (on channel zda9d07oz4): Error: Claude Code process terminated by signal SIGILL

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Illegal instruction - CPU lacks AVX support (Linux) #24456
2. Bun 1.3.6 in Claude Code 2.1.15 crashes with SIGILL on CPUs without AVX support #20116
3. v2.1.15 crashes on CPUs without AVX (regression from 2.1.14) #19907

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[briankelley]

Workaround for AVX/CPU Crash on Linux

The crash is caused by the bundled Bun runtime (Bun Canary v1.3.9) attempting to use AVX instructions despite being compiled as "baseline" (no_avx). This affects VMs and older CPUs that don't expose AVX.

Affected versions: 2.1.37+ (including current latest 2.1.39)
Working versions: 2.1.29 (current stable), 2.1.7 (haven't fully tested others)

---

Step 1: Get a working version

Stop using the installer - it downloads the broken latest build first, so you can't even downgrade. Grab a working version directly:

curl -fsSL -o ~/.local/share/claude/versions/2.1.29 "https://storage.googleapis.com/claude-code-dist-86c565f3-f756-42ad-8dfa-d59b1c096819/claude-code-releases/2.1.29/linux-x64/claude"

chmod +x ~/.local/share/claude/versions/2.1.29

Delete the symlink and use an alias instead (the installer keeps recreating that symlink pointing to latest):

rm ~/.local/bin/claude

Add to ~/.bashrc
alias claude='/home/YOUR_USER/.local/share/claude/versions/2.1.29'

---

Step 2: Lock it down before you launch

Don't run the working version yet. If your release channel is still set to "latest", it'll auto-update and pull the broken build the moment it starts.

Lock the versions directory first:
chmod 500 ~/.local/share/claude/versions/

This prevents Claude from writing new binaries. The environment variables below are supposed to help, but they didn't fully work for me:
export CLAUDE_CODE_DISABLE_AUTOUPDATE=1
export CLAUDE_AUTO_UPDATE=0

---

Step 3: Launch and switch to stable

Now you can safely run your working version. Switch from latest to stable so future updates don't pull broken builds:

Run /config inside Claude and change your release channel, or edit the config directly:

Edit ~/.claude/settings.json or ~/.claude/settings.local.json

{
"releaseChannel": "stable"
}

When you want to update later, unlock the directory temporarily (chmod 700), download the version you want, then lock it again.

---

All of the above instructions were the result of me screwing around with this all day. I can appreciate a high velocity CI/CD pipeline that forces EVERY SINGLE USER TO BE BETA TESTERS (e.g. 'latest'), but when you release a breaking version where it's not clear how to revert because the installation process downloads the broken version in order to downgrade, that's an incredibly myopic approach.

[DragonSigh]

Workaround for AVX/CPU Crash on Linux

The crash is caused by the bundled Bun runtime (Bun Canary v1.3.9) attempting to use AVX instructions despite being compiled as "baseline" (no_avx). This affects VMs and older CPUs that don't expose AVX.

Affected versions: 2.1.37+ (including current latest 2.1.39) Working versions: 2.1.29 (current stable), 2.1.7 (haven't fully tested others)

Followed your workaround, but for me even this version crashes with "CPU lacks AVX support":

user@srv01:~$ claude --dangerously-skip-permissions
============================================================
Bun v1.3.5 (1e86cebd) Linux x64 (baseline)
Linux Kernel v5.10.0 | glibc v2.31
CPU: sse42 popcnt
Args: "/home/user/.local/share/claude/versions/2.1.29" "--dangerously-skip-permissions"
Features: Bun.stderr(2) jsc no_avx2 no_avx standalone_executable
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "node:events" "node:fs" "node:fs/promises" "node:http" "node:https" "node:net" "node:os" "node:path" "node:path/win32" "node:perf_hooks" "node:process" "node:stream" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:zlib" "undici" "node:http2"
Elapsed: 330ms | User: 424ms | Sys: 133ms
RSS: 1.23GB | Peak: 0.28GB | Commit: 1.23GB | Faults: 0 | Machine: 12.53GB

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Segmentation fault at address 0x7FE0A5801F30
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/1.3.5/B_11e86cebEigggigDk0iruE+9mO6ni4pFw8s2wE66yyzFsgo+lF_8mms/D_y9us/D_y9us/D_y9us/D_y9us/D_y9us/D_y9us/DA2g+/Bhtw/v6C

Недопустимая инструкция
user@srv01:~$ claude --version
2.1.29 (Claude Code)
user@srv01:~$

[yasumorishima]

Same issue on Windows with claude remote-control

• OS: Windows 11 Pro Education 10.0.26200
• CPU: Intel Celeron N4500 (no AVX support)
• Command: claude remote-control
• Bun version: 1.3.10

CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Illegal instruction at address 0x7FF61792E900

Crash report: https://bun.report/1.3.10/e_189a8aa9AggggigDgw0n3C8sui3Cmjqi3Cm1pi3Cwyxx9Bm+pt9Bwil05BwkxmxB4vo8FmxcghMw7161DCYKERNEL32.DLLut0LCSntdll.dll4gijBA3s//Bgw0ryX

The main claude command works fine on this machine, but remote-control specifically crashes.