CLAUDE_CODE_SHELL environment variable ignored on Windows

[iandreychik]

Description

The CLAUDE_CODE_SHELL environment variable is ignored on Windows. Claude Code always uses Git Bash (/usr/bin/bash) regardless of the setting.

Steps to reproduce

1. Set CLAUDE_CODE_SHELL in ~/.claude/settings.json:

   {
     "env": {
       "CLAUDE_CODE_SHELL": "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe"
     }
   }

2. Also tried setx CLAUDE_CODE_SHELL powershell.exe (system environment variable)
3. Also tried short name powershell.exe instead of full path
4. Restart Claude Code in a new terminal window each time

Expected behavior

PowerShell is used as the shell for Bash tool calls.

Actual behavior

Git Bash (/usr/bin/bash) is always used regardless of the setting.

Environment

• OS: Windows 11 Pro for Workstations 10.0.26200
• Python: 3.13.12
• Claude Code: latest channel

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] CLAUDE_CODE_SHELL environment variable is ignored on Windows #21843
2. CLAUDE_CODE_SHELL environment variable not respected on Windows #20453
3. CLAUDE_CODE_GIT_BASH_PATH causes all commands to use Git Bash instead of parent shell #20076

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

[iandreychik]

This is not a duplicate — the linked issues form a circular chain of unresolved closures:

• CLAUDE_CODE_SHELL environment variable not respected on Windows #20453 — closed by the author after the bot flagged duplicates, no fix applied
• [BUG] CLAUDE_CODE_SHELL environment variable is ignored on Windows #21843 — auto-closed as a duplicate of CLAUDE_CODE_SHELL environment variable not respected on Windows #20453, which itself is closed without resolution
• CLAUDE_CODE_GIT_BASH_PATH causes all commands to use Git Bash instead of parent shell #20076 — still open but marked stale, no official response

None of these issues have received an Anthropic team response or fix. CLAUDE_CODE_SHELL is still ignored on Windows — Claude Code always defaults to Git Bash regardless of configuration.

This affects any Windows user who needs PowerShell (e.g., for proper security group inheritance, Docker access, or native Windows tooling). The workaround of prefixing every command with powershell.exe -Command is fragile and shouldn't be necessary when a dedicated environment variable exists for this purpose.

Requesting this be triaged by the team rather than auto-closed into the duplicate cycle.

[hersh-gupta]

I'm also hitting this issue. My setup is a bit different -- I use Cmder with cmd.exe as my shell, not PowerShell or Git Bash.
My environment:

Windows with Cmder (cmd.exe /k %CMDER_ROOT%\vendor\init.bat)
Git for Windows at C:\tools\Cmder\vendor\git-for-windows\cmd\git.exe
No Cygwin installed

Claude Code is injecting cygpath calls into bash tool executions, which fail or cause unexpected behavior since I'm not in a Cygwin/MSYS2 context. The cygpath.exe binary exists at C:\tools\Cmder\vendor\git-for-windows\usr\bin\ (bundled with Git for Windows), but it shouldn't be invoked in my workflow.

Confirming that CLAUDE_CODE_SHELL does not work to override this behavior. Would love to see proper Windows shell detection that respects the configured shell environment.

[nobul-jose]

Use case: I maintain a cross-platform tooling repo (ai-tooling) that scaffolds Claude Code, Cursor, and MCP servers across Windows and macOS. The repo provides both .ps1 and .sh variants of all setup scripts.

Pain point: On Windows, Claude Code's Bash tool is hardcoded to Git Bash. When I ask Claude Code to run a .ps1 deploy script, it can't -- it has to use powershell.exe -NoProfile -ExecutionPolicy Bypass -File "script.ps1" as a workaround from inside Git Bash. Setting CLAUDE_CODE_SHELL=powershell.exe (either as an env var or in settings.json) is silently ignored.

This makes the Windows experience noticeably worse than macOS, where the shell just works. The workaround is manageable but fragile (quoting issues, no tab completion, no native PowerShell error formatting).

Would love to see CLAUDE_CODE_SHELL respected on Windows so Claude Code can natively use PowerShell when configured.

[ZendaitaAlex]

Workaround: Switch from native binary to npm install

We hit the same EINVAL: invalid argument, open error on every Bash tool call on Windows 11. After extensive debugging, we found the root cause: the native Claude Code binary (~\.local\bin\claude.exe) uses the Bun runtime, and Bun's fs.openSync is broken on Windows.

Evidence

Debug log stack trace points to Bun:

at $3$ (B:/~BUN/root/claude.exe:1756:2307)

We verified that Node.js file operations work perfectly on the same machine, same directory, same flags. The EINVAL is Bun-specific.

Fix

Install Claude Code via npm (which uses Node.js instead of Bun):

# 1. Rename the native Bun binary so it's no longer used
rename "$env:USERPROFILE\.local\bin\claude.exe" claude-bun.exe

# 2. Install via npm (uses Node.js runtime)
npm install -g @anthropic-ai/claude-code

# 3. Delete the Unix shell script npm creates (Windows can't run it)
del "$env:APPDATA\npm\claude"  # extensionless file - Unix shell script
# Keep claude.cmd - that's the Windows-compatible launcher

After this, claude resolves to the npm version running on Node.js. Same CC version (2.1.53), Bash tool works perfectly.

Environment

• Windows 11 Pro (24H2)
• Claude Code 2.1.53 (native install)
• Node.js v24.11.0
• Git 2.53.0

What we eliminated

• File permissions ✅ (full control on temp dir)
• Missing directories ✅ (all exist)
• Windows Defender / Controlled Folder Access ✅ (disabled)
• Antivirus ✅ (none beyond Defender)
• Node.js fs.openSync ✅ (works fine with all flag combinations)

The issue is specifically in Bun's Windows implementation of openSync, not in Claude Code's logic itself.

[iandreychik]

Still reproducible on Claude Code 2.1.63 (native install, Windows 11 Pro 10.0.26200)

The CLAUDE_CODE_SHELL environment variable is still ignored. Despite the setting in ~/.claude/settings.json:

{
  "env": {
    "CLAUDE_CODE_SHELL": "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe"
  }
}

The Bash tool still runs in Git Bash (MINGW64):

• $SHELL → /bin/bash.exe
• $BASH_VERSION → 5.2.37(1)-release
• uname -a → MINGW64_NT-10.0-26200
• $PSVersionTable → empty (not PowerShell)

No change in behavior from the original report. The setting is silently ignored.

Environment

• Windows 11 Pro for Workstations (10.0.26200)
• Claude Code 2.1.63 (native install, ~/.local/bin/claude.exe)
• Node.js v24.11.0
• Git Bash 5.2.37

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.