Service principal-less authentication failed
What causes it and how to fix it:
- Exchange Online Admin API (the REST behind EXO V3) cannot be called from the browser — no CORS, and SPFx tokens lack Exchange.Manageadminapi/beta/{tenant}/InvokeCommand fails with 'Failed to fetch' even with a fake token; read Exchange config with an admin-run script and import, or use Graph message trace and mailbox reportsCause and fix →