SharePoint guest transition can cause access denied errors
Reviewed by Helen Jones
Microsoft is moving external-user authentication for SharePoint Online and OneDrive to Microsoft Entra B2B, with tenants selected automatically. From July 2026, an external collaborator without a matching Entra B2B guest account can see access denied when opening previously shared content. Microsoft says anonymous Anyone links are not affected.
A sharing link can look valid in SharePoint while the person behind it no longer has the directory record needed to authenticate. The resulting ticket may appear to be a broken link or permissions mistake even though the site and file permissions have not changed. Small Microsoft 365 teams need to find the exposed guests before the rollout reaches their tenant. Proactive cleanup is cheaper than diagnosing each access-denied report after a supplier, client or contractor is already blocked.
Analysis
Run the site-level external sharing report and use its User E-mail column to identify invitees without an Entra B2B guest account. Create the missing guest accounts or reshare a representative item, then test access with an external user.
Source note
Pulse published by Collab365 Spaces, reviewed by Helen Jones on . Cite as "SharePoint guest transition can cause access denied errors", Collab365 Spaces.