[BUG] — Claude Code Windows v2.1.175 launches as Bun instead of Claude

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?

Bug Report — Claude Code Windows v2.1.175 launches as Bun instead of Claude

For: https://github.com/anthropics/claude-code/issues
Date: 2026-06-12
Reporter env: Windows 11 Home Single Language 10.0.26200, PowerShell 5.1

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What Should Happen?

Summary

claude.exe v2.1.175 installed via the official PowerShell installer (irm https://claude.ai/install.ps1 | iex) on Windows runs the embedded Bun runtime instead of the Claude Code launcher. The user sees Bun's Usage: bun <command> help text and claude --version reports 1.3.14 (Bun's version). Reinstalling from the latest channel reproduces the broken binary. Switching to the stable channel resolves it (lands on 2.1.153).

Steps to reproduce

1. Fresh / existing install of Claude Code on Windows.
2. Auto-update advances ~/.local/bin/claude.exe to 2.1.175.
3. Run claude in any PowerShell window.

Expected

Claude Code TUI launches.

Actual

PS> claude
Bun is a fast JavaScript runtime, package manager, bundler, and test runner. (1.3.14+2a41ca974)
Usage: bun <command> [...flags] [...args]
...
PS> claude --version
1.3.14

Diagnostics

• where.exe claude → C:\Users\myide\.local\bin\claude.exe (correct path)
• Get-Command claude -All | Format-List →
• Product: Claude Code
• ProductVersion: 2.1.175.0
• FileDescription: Claude Code
• InternalName: bun
• BUN_BE_BUN env var: not set (User / Machine / Session all empty)
• No Thai characters in path required to reproduce (occurs in plain C:\Users\myide)
• Reinstall via irm https://claude.ai/install.ps1 | iex → still 2.1.175, same broken behavior

Workaround that works

Remove-Item "$env:USERPROFILE\.local\bin\claude.exe" -Force
Remove-Item "$env:USERPROFILE\.local\share\claude" -Recurse -Force
& ([scriptblock]::Create((irm https://claude.ai/install.ps1))) stable
# close all PowerShell windows, reopen
claude --version   # 2.1.153 (Claude Code) — OK

Hypothesis

The bundled launcher trampoline that should execute the embedded Claude Code JS appears to be missing or no-op in the 2.1.175 Windows build, so execution falls through to the embedded Bun CLI's default help screen. Metadata is still stamped correctly, which is why detection only surfaces at runtime.

Impact

• Users on latest channel cannot launch Claude Code at all.
• irm | iex reinstall does not help (latest still serves the broken artifact).
• Workaround requires knowing the stable channel syntax — not obvious from the install script's default invocation.

Suggested fix / mitigation

1. Yank 2.1.175 from latest or republish with a working launcher.
2. Have the installer's --version smoke-test refuse to finalize if claude --version reports a Bun version string.
3. Document the stable channel installer syntax (& ([scriptblock]::Create((irm https://claude.ai/install.ps1))) stable) more prominently — currently easy to miss.

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Error Messages/Logs

Windows PowerShell
Copyright (C) Microsoft Corporation. All rights reserved.
Install the latest PowerShell for new features and improvements! https://aka.ms/PSWindows
PS C:\Users\myide\Downloads\เทคนิคชุมพร> claude
Bun is a fast JavaScript runtime, package manager, bundler, and test runner. (1.3.14+2a41ca974)
Usage: bun <command> [...flags] [...args]
Commands:
  run       ./my-script.ts       Execute a file with Bun
            lint                 Run a package.json script
  test                           Run unit tests with Bun
  x         bun-repl             Execute a package binary (CLI), installing if needed (bunx)
  repl                           Start a REPL session with Bun
  exec                           Run a shell script directly with Bun
  install                        Install dependencies for a package.json (bun i)
  add       hono                 Add a dependency to package.json (bun a)
  remove    browserify           Remove a dependency from package.json (bun rm)
  update    react                Update outdated dependencies
  audit                          Check installed packages for vulnerabilities
  outdated                       Display latest versions of outdated dependencies
  link      [<package>]          Register or link a local npm package
  unlink                         Unregister a local npm package
  publish                        Publish a package to the npm registry
  patch <pkg>                    Prepare a package for patching
  pm <subcommand>                Additional package management utilities
  info      lyra                 Display package metadata from the registry
  why       @remix-run/dev       Explain why a package is installed
  build     ./a.ts ./b.jsx       Bundle TypeScript & JavaScript into a single file
  init                           Start an empty Bun project from a built-in template
  create    vite                 Create a new project from a template (bun c)
  upgrade                        Upgrade to latest version of Bun.
  feedback  ./file1 ./file2      Provide feedback to the Bun team.
  <command> --help               Print help text for command.
Learn more about Bun:            https://bun.com/docs
Join our Discord community:      https://bun.com/discord
PS C:\Users\myide\Downloads\เทคนิคชุมพร> test
test : The term 'test' is not recognized as the name of a cmdlet, function, script file, or operable program. Check
the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:1
+ test
+ ~~~~
    + CategoryInfo          : ObjectNotFound: (test:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException
PS C:\Users\myide\Downloads\เทคนิคชุมพร>

Steps to Reproduce

claude_bug_report_2026-06-12.md

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.153 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_