[BUG] OAuth error: Request failed with status code 500

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?

<img width="1212" height="936" alt="Image" src="https://github.com/user-attachments/assets/21f622a4-8ad7-4d19-9fd1-28f6bea264fc" />

seeing this error on authorizing via browser: OAuth error: Request failed with status code 500

What Should Happen?

login should proceed normally

Error Messages/Logs

OAuth error: Request failed with status code 500

Steps to Reproduce

1. fresh install v2.1.15
2. $ claude
3. copy and paste the login url to browser
4. copy the auth key back in the claude code
5. see the error

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

v2.1.12

Claude Code Version

v2.1.15

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_