Claude Code API not connecting

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 — ECONNRESET on all connections (macOS Sequoia 15.3.1)
Version: Claude Code v2.1.133
OS: macOS Sequoia 15.3.1 (MacBook Air)
Problem: Claude Code fails to connect every time with:
"Failed to connect to api.anthropic.com: ECONNRESET"
What I've tried:

Multiple relaunches
Wiped ~/.claude and did a clean start
--verbose flag gives no additional detail
/login and /feedback commands also fail to connect

What works fine:

curl to api.anthropic.com connects successfully
A test POST to /v1/messages returns a proper JSON auth error (meaning the API is reachable)
No proxy environment variables set (HTTP_PROXY, HTTPS_PROXY, NO_PROXY all empty)

Conclusion: Network connectivity is fine. The issue appears to be specific to how Claude Code itself handles TLS/connections on this machine, not a network or firewall problem.

What Should Happen?

Claude Code should connect to API and provides response.

Error Messages/Logs

API Error: Unable to connect to API (ECONNRESET)

Steps to Reproduce

Go to Claude Code and type in any prompt.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Yesterday

Claude Code Version

2.1.133 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_