[BUG] Intermittent 500 Internal Server Errors during Claude Code sessions

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?

Getting repeated 500 Internal Server Error responses during Claude Code sessions. The errors occur intermittently — sometimes back-to-back, sometimes after a period of normal operation. Retrying the same message usually works on the next attempt.

Error Message
API Error: 500 {"type":"error","error":{"type":"api_error","message":"Internal server error"},"request_id":"req_011CYV9wtaSY9Hjp2RNNX4qK"}

Environment
OS: macOS 15 (Darwin 25.3.0)
Architecture: Apple Silicon (arm64)
Model: claude-opus-4-6
Date: 2026-02-25

What Should Happen?

Reproduction
Occurs during long coding sessions with multi-step tasks
Happens when launching Task tool subagents (Plan, Explore agents)
Also occurs during regular conversation turns
No specific trigger — appears random/intermittent
Multiple occurrences in a single session
Impact
Breaks workflow mid-task, requiring message retry
Subagent tasks fail completely and need to be re-launched
Context can be lost when errors occur during compaction

Error Messages/Logs

Request IDs
req_011CYV9wtaSY9Hjp2RNNX4qK
req_011CYVANMpxA9V4NFZQCnPBY
req_011CYVB9ECa1wsJJuQ7uuhso
req_011CYVASpF4KBTFcoBis9z76
req_011CYVANPkJ2iWfMrZAR4YFg

Steps to Reproduce

[What prompt or task did you give Claude Code?]
[What was the CLI attempting to do right before the crash (e.g., reading a specific file, running a bash command, searching)?]
The 500 error was returned.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.4173 (12766c) 2026-02-24T15:04:14.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_