[BUG] error codes (AADSTS9000411 duplicate prompt, AADSTS50011 redirect URI mismatch)

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?

This is a plugin infrastructure issue — the MS365 MCP plugin is generating dynamic localhost ports that aren't registered in the Azure app. I can't fix this from here. Error codes (AADSTS9000411 duplicate prompt, AADSTS50011 redirect URI mismatch)

What Should Happen?

Outlook Business Account Authentication Fails.

Error Messages/Logs

Error codes (AADSTS9000411 duplicate prompt, AADSTS50011 redirect URI mismatch)

Steps to Reproduce

Check my Outlook inbox at [TorontoBikeFest@Outlook.com](mailto:TorontoBikeFest@Outlook.com) and tell me the 3 most recent emails

I need to authenticate with Microsoft 365 first. Let me start the OAuth flow.

Please open the link below in your browser to authorize access to your Microsoft 365 account:

Click here to authorize MS365

Once you complete the sign-in and authorization in your browser, let me know and I'll fetch your inbox.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

4.6

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_