SharePoint Old Guest Sign-In Retires in October: Admin Guide

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Passcode Retirement, Entra B2B Migration, and Guest Access Remediation

Microsoft is ending legacy authentication methods for external guests across Microsoft 365 tenants.

Starting in mid-October 2026, SharePoint old guest sign-in using legacy passcodes stops working completely. Instead, Microsoft automatically moves all external file sharing to Microsoft Entra B2B guest accounts. Specifically, this change affects commercial tenants worldwide, and Microsoft offers no opt-out switch. Microsoft expects the rollout to finish by the end of November 2026.

Who Is Impacted by the Retirement?

First, knowing which external users face access issues helps IT teams fix problems early:

  • Ad hoc external users: External guests who received custom links under the old system without an Entra guest account will see access denied messages.
  • Anyone links unaffected: Public “Anyone with the link” permissions continue working without changes.
  • Sovereign cloud timeline: However, sovereign government clouds remain excluded from this initial October phase.
  • Entra email passcodes stay: In addition, standard Microsoft Entra email passcodes remain fully supported for guest sign-ins.

Benefits of Microsoft Entra B2B Migration

Second, moving guest authentication to Microsoft Entra B2B improves company security:

  • Central directory control: Guest users show up directly inside central directory lists.
  • Conditional access rules: Therefore, admins can apply multi-factor checks and location rules to guest sessions.
  • Unified audit tracking: As a result, guest sign-ins log directly to Entra security logs for easier tracking.

Remediation Action Plan for IT Administrators

To prevent key business partners from running into blocked links, IT teams should complete four steps:

  • Run sharing reports: Generate site external sharing reports to find active guests without Entra accounts.
  • Pre-create guest accounts: Create required guest accounts manually or reshare items before the cutoff.
  • Verify Entra settings: Confirm that email passcode settings remain enabled in Entra settings.
  • Train helpdesk staff: Additionally, teach support teams how simple resharing fixes guest access issues fast.

How our team supports your directory governance:

  • External User Audits: We find old guest links and match external users to active Entra identities.
  • Guest Access Policies: We help you set up guest policies and access rules to secure shared files.

Fix your guest settings before legacy passcodes expire. Reach out to our team today to evaluate your guest sharing setup.

Graphic with text: SharePoint's Old Guest Sign-In Retires in October. Simple SharePoint, a division of Rego Consulting.

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