[BUG] API Error 500 - Internal Server Error on all requests

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?

Bug Description
Claude Code returns a persistent API 500 Internal Server Error, making it unable to process requests.

Error Message

API Error: 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"},"request_id":"req_011Ca5kE1cN76fPSj3AE77zU"}

Steps to Reproduce

1. Open Claude Code in terminal
2. Send any prompt
3. Error returned immediately

Expected Behavior
Normal response from Claude.

Actual Behavior
Request fails with 500 api_error on every attempt.

Environment

• Authentication: Claude Max subscription (OAuth)
• Platform: Windows / WSL
• Claude Code version: latest

Notes
Retried multiple times. Issue persists across new sessions. Request ID attached for server-side tracing.

What Should Happen?

Claude Code should process the request normally and return a response from the model.

Error Messages/Logs

API Error: 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"},"request_id":"req_011Ca5kE1cN76fPSj3AE77zU"}

Steps to Reproduce

1. Open terminal and launch Claude Code
2. Authenticate via Claude Max subscription (OAuth)
3. Type any prompt (e.g. "Hello")
4. Hit Enter
5. Error is returned immediately instead of a model response
6. Retried multiple times across new sessions — issue persists

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.109 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Cursor

Additional Information

_No response_