[BUG] Authorization failed: malformed redirect URI (single slash in https:/)

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?

When attempting to authenticate with claude login, the OAuth flow fails with the following error:

Authorization failed
Redirect URI https:/platform.claude.com/oauth/code/callback is not supported by client.

The redirect URI contains a malformed protocol — https:/ (single slash) instead of https:// (double slash).

What Should Happen?

The redirect URI should be https://platform.claude.com/oauth/code/callback and authentication should complete successfully.

Error Messages/Logs

Authorization failed
  Redirect URI https:/platform.claude.com/oauth/code/callback is not supported by client.

Steps to Reproduce

1. Run claude login
2. Browser opens for OAuth authentication
3. After authorizing, the redirect fails with the error above

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.83

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• No proxy or VPN active
• Issue persists after claude logout and re-login