Troubleshooting case study
Conditional Access: error 53003
Sign-in error 53003 traced to an external-identity security-information policy scoped to all users. Restricting scope to guest/external users restored the internal test sign-in while MFA remained effective. A Graph licensing-metadata discrepancy remains documented.
Environment
Personal Microsoft 365 E5 Developer tenant with Exchange Online, Defender, Conditional Access, and test identities.
Diagnostic process, findings & corrective action
Sign-in error 53003 traced to an external-identity security-information policy scoped to all users. Restricting scope to guest/external users restored the internal test sign-in while MFA remained effective. A Graph licensing-metadata discrepancy remains documented.
Validation & outcome
Delivery traces, Defender Explorer, audit logs, successful MFA sign-in evaluation, and effective E5 licensing support the completed lab scope.
Lessons & limitations
Personal Microsoft 365 Developer tenant. The evidence README is synchronized with the current COMPLETE project status. Group-license UI evidence and Graph metadata were not fully reconciled; the discrepancy remains part of the claim boundary and is not represented as resolved.
The evidence supports the specific scenario. Unestablished root causes are not presented as confirmed.