Fix Windows subprocess CLI detection (WinError 193) #253
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On Windows, npm creates both 'claude' (a bash script) and 'claude.cmd' (a batch file).
The SDK was using shutil.which('claude'), which returns the bash script that cannot be
executed as a Win32 application, causing OSError: [WinError 193] %1 is not a valid Win32 application.
This fix:
- Uses 'claude.cmd' on Windows and 'claude' on other platforms
- Updates fallback location paths to include .cmd extension on Windows
- Adds common Windows npm installation path (AppData/Roaming/npm)
Tested on Windows 11 with Python 3.12 and claude-agent-sdk 0.1.3
Co-Authored-By: Claude <[email protected]>
ashwin-ant
approved these changes
Oct 16, 2025
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Fixes #252
Summary
Fixes the issue where the SDK fails to start on Windows with
OSError: [WinError 193] %1 is not a valid Win32 application.Problem
On Windows, npm creates both
claude(bash script) andclaude.cmd(batch file). The SDK was usingshutil.which("claude"), which returns the bash script that cannot be executed as a Win32 application on Windows.Changes
_find_cli()insubprocess_cli.pyto useclaude.cmdon Windows instead ofclaude.cmdextension on Windows platformsAppData/Roaming/npm)Testing
claude)Implementation Details
The fix detects the platform using
sys.platform == "win32"and conditionally:claude.cmdon Windows,claudeelsewhereCo-Authored-By: Claude [email protected]