[BUG] Claude Code process exits with code 3221225477 (0xC0000005) on Windows 11 25H2 during file operations, with "unsupported Windows version" dialog

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?

The Claude Code VS Code extension crashes with "Error: Claude Code process exited with code 3221225477" (0xC0000005 / STATUS_ACCESS_VIOLATION).

The panel initially loads and authentication succeeds. A session can be started and the first message sent successfully. The crash occurs specifically when Claude attempts a file operation (e.g. reading a file). At the exact moment of the crash, a native Windows dialog appears simultaneously stating: "This program doesn't support the Windows version installed on your computer" (German: "Dieses Programm unterstützt die auf Ihrem Computer installierte Windows-Version nicht.").

This happens consistently and reproducibly on every session once a file operation is attempted.

Notably, the standalone CLI works perfectly when run directly from PowerShell (outside VS Code) — claude --version, claude doctor, and interactive claude sessions including file reads/writes all work without issue. The crash only occurs when the process is spawned by the VS Code extension.

Troubleshooting already attempted without success:

• Full reinstall of VS Code and the Claude Code extension
• Full reinstall of the CLI via npm (@anthropic-ai/claude-code), including cache clean
• Full reinstall via the official installer (irm https://claude.ai/install.ps1 | iex)
• Manually setting "Claude Process Wrapper" in extension settings to point directly to the working claude.exe
• Verified the claude.exe file has a valid, current digital signature from Anthropic, PBC (signed July 2, 2026)
• Checked Windows Event Viewer for Application Error entries — none found referencing claude.exe
• Ruled out ARM architecture (system is x64)
• claude doctor reports all diagnostics green (npm-global, version 2.1.199)

What Should Happen?

Claude Code should perform file operations (reading files, etc.) inside the VS Code panel without crashing, and without triggering a Windows "unsupported version" compatibility dialog.

Error Messages/Logs

Steps to Reproduce

1. Open VS Code on Windows 11 25H2 (Build 26200.8655)
2. Open the Claude Code panel in the sidebar
3. Log in via "Claude.ai Subscription" — login completes successfully
4. Start a new session in a local project folder
5. Send a message asking Claude to look at a file, e.g. "hallo schau dir bitte die architektur datei an" (asks Claude to look at an architecture file)
6. Claude begins processing (visible in output log: multiple messages exchanged, ~20 messages processed)
7. At the moment Claude attempts to read/access the file, the process crashes:

• VS Code shows: "Error: Claude Code process exited with code 3221225477"
• Simultaneously, a native Windows dialog appears: "This program doesn't support the Windows version installed on your computer"

1. The session becomes unusable; reopening the panel or starting a new session reproduces the same crash on the next file operation

Note: Running the identical CLI directly in a standalone PowerShell window (outside VS Code) — including reading/writing files — works without any issue. The crash is specific to the VS Code extension spawning the process.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.199

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

• OS: Windows 11 Home, Version 25H2 (Build 26200.8655)
• Architecture: x64
• Claude Code version: 2.1.199 (npm-global install)
• Install path: C:\Users\[user]\AppData\Roaming\npm\node_modules\@anthropic-ai\claude-code\bin\claude.exe