Cause (Documented platform behavior): Documented deliberate security hardening.
Fix status: documented_behavior
Misleading approaches:
- Reinstalling via npm: the npm install creates exactly the claude.cmd shim that is refused.
Evidence (public sources, summarized; not reproduced by this contributor):
- https://code.claude.com/docs/en/agent-sdk/troubleshooting (official_docs, 2026-09, documented_behavior): Agent SDK troubleshooting quotes the full refusal message, explains cmd.exe re-parsing risk, the two cases that reach it, and that before claude-agent-sdk 0.2.124 batch scripts were spawned through cmd.exe without the check.
Search phrasings: Refusing to execute batch script claude.cmd; claude-agent-sdk windows CLIConnectionError batch script
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Python agent on Windows (often ARM64 or with cli_path set to npm's claude.cmd) fails at connect after upgrading the SDK.
- Context
- Product: Claude Agent SDK Component: Python SDK CLI launch on Windows Operation: ClaudeSDKClient.connect / query() with cli_path or npm claude.cmd shim Affected versions: >=0.2.124 Environment: Windows Exception: claude_agent_sdk.CLIConnectionError Packages: claude-agent-sdk >=0.2.124 Trigger: Since 0.2.124 the SDK refuses .bat/.cmd CLI paths as command-injection hardening; happens when cli_path points at a batch shim, or no bundled/native claude.exe exists (e.g. source install on ARM64 Windows with only the npm shim on PATH).
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- Refusing to execute batch script 'C:\\Users\\you\\AppData\\Roaming\\npm\\claude.cmd': Windows runs .bat/.cmd files via cmd.exe, which can execute commands injected through CLI arguments, and no reliable escaping for cmd.exe exists.
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Claude Agent SDK Python on Windows] CLIConnectionError 'Refusing to execute batch script ...claude.cmd' (claude-agent-sdk >= 0.2.124)
Recommended action: Point cli_path at a native claude.exe or remove cli_path (discovery is skipped while set); install Claude Code natively (irm https://claude.ai/install.ps1 | iex) or use the x64 wheel that bundles claude.exe.
Option: Use a native claude.exe [evidence: official_recommended_action]
Applies when: Claude Agent SDK / Python SDK CLI launch on Windows
Steps:
1. Remove cli_path or set it to claude.exe
2. Install Claude Code natively
3. On x64 install the platform wheel
Expected: Request accepted / failure becomes diagnosable
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- c78688da-7e69-492e-aa44-b559316fb466
- Proposed action
- Recommended action: Point cli_path at a native claude.exe or remove cli_path (discovery is skipped while set); install Claude Code natively (irm https://claude.ai/install.ps1 | iex) or use the x64 wheel that bundles claude.exe. Option: Use a native claude.exe [evidence: official_recommended_action] Applies when: Claude Agent SDK / Python SDK CLI launch on Windows Steps: 1. Remove cli_path or set it to claude.exe 2. Install Claude Code natively 3. On x64 install the platform wheel Expected: Request accepted / failure becomes diagnosable
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.