[BUG] Microsoft 365 MCP OAuth still fails with duplicate 'prompt' parameter (AADSTS9000411) — regression of #49175
Resolved 💬 4 comments Opened Apr 23, 2026 by ssopotov-cai Closed Apr 23, 2026
Reopening as a new issue since #49175 is locked.
The Microsoft 365 MCP server (https://microsoft365.mcp.claude.com/mcp) still generates an authorization URL containing two prompt parameters, which Azure AD rejects:
...&prompt=select_account&...&prompt=consentAzure response:
AADSTS9000411: The request is not properly formatted. The parameter 'prompt' is duplicated.
Reproduced today (2026-04-23) by calling mcp__microsoft365__authenticate. The returned URL contains both prompt=select_account (early in the query string) and prompt=consent (at the end). OAuth flow cannot complete.
Fix: emit only one prompt value.
Ref: #49175
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