[BUG] Claude Desktop crash on broker login

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?

Authenticating via the Entra broker flow for a custom third-party MCP server (websearch) causes Claude Desktop to crash on Windows. The app was working correctly on version 1.49585.0. The last log line before the crash is shown below; nothing is logged afterward, and the app crashes silently at this point.

What Should Happen?

The Entra broker authentication grant should complete successfully and the custom MCP server should authenticate, as it did in 1.49585.0.

Error Messages/Logs

2026-09-11 11:53:55 [info] [custom3p-mcp:entra-broker] starting Entra broker grant { server: 'websearch', tenantId: '56ac8205-a37e-4856-a53f-686943febf7b' }

Steps to Reproduce

Configure a custom third-party MCP server (websearch) using broker-based auth (Entra/Azure AD), tenantId 56ac8205-a37e-4856-a53f-686943febf7b.
Trigger authentication (e.g. open the server / send a request requiring auth).
Observe: app crashes immediately after the "starting Entra broker grant" log line, with no further output and no error dialog.

Claude Model

_No response_

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.49585.0

Claude Code Version

1.52386.0

Platform

AWS Bedrock

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_