[BUG] 500 API Internal Server Error

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?

Claude Code CLI is currently unusable: every request returns an API 500 (“Internal server error”), regardless of prompt content or which directory/repo I run it from. This happens even for trivial prompts and blocks all normal CLI usage.

What Should Happen?

Claude Code should successfully send the prompt to the API and return a normal assistant response (or a user-actionable client-side error if something is misconfigured). A generic “Internal server error” for all prompts should not happen.

Error Messages/Logs

API Error: 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"},"request_id":"req_011CY11TErVNj n5MhJPSbzt1"}

Steps to Reproduce

1. Install/upgrade Claude Code CLI (observed on v2.1.38).
2. Open Terminal.app on macOS.
3. From any directory (any repo or even an empty folder), run Claude Code in either interactive or one-shot mode,
4. Then enter any prompt (example minimal prompt: hi), or:
5. Observe the CLI fails with an API 500 “Internal server error” (see logs above).

Notes:

• Reproducible with any prompt content.
• Reproducible from any working directory / repository.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

n/a

Claude Code Version

2.1.38 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

<img width="1440" height="900" alt="Image" src="https://github.com/user-attachments/assets/eeb5a641-2715-447e-88a0-0df2499050b7" />
<img width="1440" height="900" alt="Image" src="https://github.com/user-attachments/assets/b49366b4-455a-4f36-a890-16b851d7625b" />