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Claude Code Issues / #26723

[BUG] Bun v1.3.10 crashes with "panic: incorrect alignment" on Windows 11 ARM64 (v2.1.47)

Resolved 💬 29 comments Opened Feb 18, 2026 by afram123 Closed Apr 17, 2026
💡 Likely answer: A maintainer (claude[bot], contributor) responded on this thread — see the highlighted reply below.

This issue will be fixed in the next version of Claude Code.

Via https://github.com/oven-sh/bun/pull/27290

Original issue:

------

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 v2.1.47 crashes repeatedly with a Bun runtime panic on Windows 11 ARM64. The crash is 100% reproducible — it occurs after ~80–150 seconds of runtime regardless of what command is being executed. Even trivial operations trigger it if the session has been running long enough.

The crash always produces the identical signature:

  • panic(thread XXXXX): incorrect alignment
  • RSS at crash: 0.64–0.78 GB (machine has 34 GB — not memory pressure)
  • Crash happened 5 consecutive times in one session

What Should Happen?

Claude Code should run without crashing on Windows 11 ARM64. Previous versions worked fine on the same machine.

Error Messages/Logs

Bun v1.3.10 (1423d3c8) Windows arm64
Windows v.win11_dt
CPU: neon fp aes crc32 atomics
Args: "C:\Users\...\claude.exe"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) fetch(91) jsc spawn(64) standalone_executable process_dlopen(3) yaml_parse(4)
Elapsed: 246271ms | User: 19218ms | Sys: 4750ms
RSS: 0.72GB | Peak: 0.94GB | Commit: 0.99GB | Faults: 1090072 | Machine: 33.90GB

panic(thread 5184): incorrect alignment
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

https://bun.report/1.3.10/W_11423d3cmgkgEugogCwmzrfwl0uiBgyvBw32CwmvBo7xB44wCwvhgmCw236lC4i16lCg6xjkBgsjufCYKERNEL32.DLLg0jCCSntdll.dlloqi1BA0eNrLzEvOLypKTS5RSMzJTM/LTc0rAQBMcwep

Steps to Reproduce

  1. Install Claude Code v2.1.47 on Windows 11 ARM64
  2. Run claude in a terminal
  3. Execute any command (bash, file read, or even just wait idle)
  4. After ~80–150 seconds of accumulated runtime, Bun panics with "incorrect alignment"
  5. Crash is 100% reproducible — happened 5 consecutive times

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — previous version before 2.1.47

Claude Code Version

2.1.47 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Bun crash report URL (identical every time):
https://bun.report/1.3.10/W_11423d3cmgkgEugogCwmzrfwl0uiBgyvBw32CwmvBo7xB44wCwvhgmCw236lC4i16lCg6xjkBgsjufCYKERNEL32.DLLg0jCCSntdll.dlloqi1BA0eNrLzEvOLypKTS5RSMzJTM/LTc0rAQBMcwep

This started recently with the current version — same machine previously worked without crashes. Likely a regression in the Bun build shipped with Claude Code.

View original on GitHub ↗

29 Comments

Ben-CA · 4 months ago

I'm having a similar issue. With v2.1.47 on Windows 11, which I installed about an hour ago, it has frozen/crashed my terminal 3 times on me so far, whereas the last version I was running never crashed. (v2.1.39?)

github-actions[bot] · 4 months ago

Found 1 possible duplicate issue:

  1. https://github.com/anthropics/claude-code/issues/26724

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

afram123 · 4 months ago

@Ben-CA I just downgraded back to v2.1.45 and it works fine.

rfmsanz-ethan · 4 months ago

Yes. Rolling back to 2.1.45 works. Definitely a regression.

Ben-CA · 4 months ago

I just downgraded back to v2.1.45 - hope that fixes it

hithereiamaliff · 4 months ago

I rolled back to v2.1.45 from v2.1.47. It worked for me. Hopefully they would fix this for the next version.

sitefinitysteve · 4 months ago

How'd you downgrade that fixed it?

curl -fsSL https://claude.ai/install.cmd -o install.cmd && install.cmd 2.1.45 && del install.cmd

✔ Claude Code successfully installed!

Version: 2.1.45

...

Bun Canary v1.3.10-canary.63 (1979c945) Windows arm64
Windows v.win11_dt
CPU: neon fp aes crc32 atomics
Args: "claude"
Features: jsc standalone_executable
Elapsed: 76ms | User: 15ms | Sys: 78ms
RSS: 69.98MB | Peak: 69.98MB | Commit: 0.30GB | Faults: 17360 | Machine: 42.94GB

panic(main thread): Segmentation fault at address 0xE005D007C009703A
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

EDIT FOR OTHERS

Remove it, then run that command

Remove-Item -Path "$env:USERPROFILE\.local\bin\claude.exe" -Force
Remove-Item -Path "$env:USERPROFILE\.local\share\claude" -Recurse -Force

WilliamCFF · 4 months ago

To downgrade, use this command npm install -g @anthropic-ai/claude-code@2.1.45

GSonofNun · 4 months ago

Still happening for me with 2.1.49

Ben-CA · 4 months ago

I downgraded to 2.1.45, was fine there. Later upgraded to 2.1.49, same problem again. Downgraded again.

sitefinitysteve · 4 months ago

Honestly at this point just stay on npm, native has been so unbelievably flakey on and off

Leilight · 4 months ago

这条信息用于提升 #27079 的保留价值：

可稳定复现的是 Windows 11 ARM64 下的崩溃，不是偶发配置问题。

环境：

  • OS: Windows 11 ARM64
  • RAM: 8.58GB
  • VS Code: 1.109.5
  • Claude Code: 2.1.49 (win32-arm64)
  • 内置 Bun: v1.3.10

关键报错：

  • Claude Code process exited with code 3
  • 日志反复出现：panic(thread XXXX): incorrect alignment
  • oh no: Bun has crashed. This indicates a bug in Bun
  • 复现时会话页失效/消失

这看起来是 Bun 在 ARM64 的 alignment 缺陷导致的 runtime 问题。
如果需要我可以再补齐完整时间戳日志片段用于进一步定位。

JNO-DEVHUB · 4 months ago

Problem besteht auch bei Version v2.1.45!

<img width="727" height="785" alt="Image" src="https://github.com/user-attachments/assets/48010347-cd78-4a9f-bbc9-7fd4d79ecb67" />

alvareando · 4 months ago

To solve it you should downgrade to 2.1.45. I did so using the native installer. Then on my .claude settings.json, I set "autoUpdatesChannel": "stable" instead of "latest".

The commands for my Windows Arm machine were:

& ([scriptblock]::Create((irm https://claude.ai/install.ps1))) 2.1.45

And then changed my settings.json inside .claude to:
"autoUpdatesChannel": "stable"

Jarred-Sumner · 4 months ago

This issue will be fixed in the next version of Claude Code.

From https://github.com/oven-sh/bun/pull/27290

ChrisGarty · 4 months ago

Thanks for getting this fixed!

SandorDobi · 4 months ago

The issue is still live in 2.1.50

scrossle · 4 months ago

Confirmed: Bun 1.3.10 regression on ARM64 — 1.3.9 works fine

Tested on Windows 11 ARM64 (Qualcomm Snapdragon X, ARMv8 Family 8 Model 1 Revision 201) with Claude Code v2.1.50.

The bundled claude.exe SFE (Bun 1.3.10) crashes with panic: incorrect alignment after ~80 seconds, consistent with other reports here.

Workaround: run cli.js through system Bun 1.3.9

  1. Install system Bun (installs 1.3.9): powershell -c "irm bun.sh/install.ps1 | iex"
  2. Install Claude Code via npm: npm install --prefix ~/claude-workaround @anthropic-ai/claude-code
  3. Run via system Bun: ~/.bun/bin/bun.exe ~/claude-workaround/node_modules/@anthropic-ai/claude-code/cli.js

This has been running stable for 10+ minutes with no crash, confirming:

  • The bug is in Bun 1.3.10's runtime, not Claude's JS code
  • Bun 1.3.9 does not have the alignment issue on ARM64
  • The crash is on a ~82 second timer, not at startup

This is a narrower workaround than downgrading to Claude Code v2.1.45 — you get the latest Claude Code version but avoid the broken Bun runtime.

rfmsanz-ethan · 4 months ago
The bundled claude.exe SFE (Bun 1.3.10) crashes with panic: incorrect alignment after ~80 seconds, consistent with other reports here. Workaround: run cli.js through system Bun 1.3.9 1. Install system Bun (installs 1.3.9): powershell -c "irm bun.sh/install.ps1 | iex" 2. Install Claude Code via npm: npm install --prefix ~/claude-workaround @anthropic-ai/claude-code 3. Run via system Bun: ~/.bun/bin/bun.exe ~/claude-workaround/node_modules/@anthropic-ai/claude-code/cli.js This is a narrower workaround than downgrading to Claude Code v2.1.45 — you get the latest Claude Code version but avoid the broken Bun runtime.

Thanks. @scrossle

I am using this as a temporary workaround until Anthropic bundles an older version of bun (or a newer, fixed version).

jakubcebula · 4 months ago

Same crash on Microsoft Surface with Snapdragon X Elite X1E80100, Windows 11 ARM64. Affects both VS Code extension and terminal CLI.

joshvermette · 4 months ago
Same crash on Microsoft Surface with Snapdragon X Elite X1E80100, Windows 11 ARM64. Affects both VS Code extension and terminal CLI.

Running same machine and can confirm downgrading to 2.1.45 fixed it for me

jakubcebula · 4 months ago

With the new version (v2.1.53), Claude Code works fine for me in the VS Code terminal on Windows 11 ARM64 — no more crashes.

Note: I had to disable the Claude Code Extension as the Claude Code chat within it was not working. Running Claude Code directly in the terminal (claude) works fine as a workaround.

ChrisGarty · 4 months ago

Downgrading from 2.1.51 to 2.1.45 was a fantastic move. Thanks for the tips on that folks! And good to know that 2.1.53 is still broken for ARM64.
I see 2.1.56 is now available, but I'm waiting until this bug is fixed before upgrading.

rfmsanz-ethan · 4 months ago

I am currently testing 2.1.61 and no crashes yet.

rfmsanz-ethan · 4 months ago

Looks like the release version of Bun 1.3.10 officially supports Windows arm64. I'm wondering if Anthropic was bundling a pre-release build that didn't have the Windows ARM support completed or something...especially since their packaged version of 1.3.10 in CC 2.1.47 was before Bun 1.3.10 actually released on Bun's github.

ilaikim99 · 4 months ago

The crash is in Bun 1.3.10's ARM64 runtime, not Claude's code — it fires on a ~80s timer regardless of what's running. Two options: downgrade to Claude Code v2.1.45, or run the latest Claude Code JS through system Bun 1.3.9 which doesn't have the alignment bug. Can see full details: https://cacheoverflow.dev/blog/BxRON4lw

rfmsanz-ethan · 4 months ago
The crash is in Bun 1.3.10's ARM64 runtime, not Claude's code — it fires on a ~80s timer regardless of what's running. Two options: downgrade to Claude Code v2.1.45, or run the latest Claude Code JS through system Bun 1.3.9 which doesn't have the alignment bug. Can see full details: https://cacheoverflow.dev/blog/BxRON4lw

Bun 1.3.10 release version shipped with the fix for this issue (Bun commit 7baf50f379a7a176f8ec50dac8f7638b2c1ed36e). At least as of CC 2.1.61, the Bun that comes packaged in the CC native install binary has this updated version of Bun 1.3.10 and therefore, the issue seems to be resolved. Theres no need to use npm/system bun or downgrade to CC 2.1.45 anymore.

claude[bot] contributor · 3 months ago

This issue was fixed as of version 2.1.53.

github-actions[bot] · 2 months ago

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.