Published: 16 July 2026. Source: Microsoft 365 Message Center MC1402118 / Microsoft Learn: Manage site collection administrators
A single point of failure is exactly what Microsoft is trying to close with MC1402118. Every SharePoint Online site, whether it is a standalone communication site or one connected to a Microsoft 365 group, must now carry at least two active owners. Sites that do not meet this bar are flagged in the SharePoint admin centre, and the flag applies retroactively to sites created long before the policy existed.
What the Message Centre Post Says
MC1402118 describes a phased rollout. In the first phase, the SharePoint admin centre surfaces a new "Ownership" column across the active sites list, flagging any site with fewer than two owners. In the second phase, currently unscheduled at time of writing, Microsoft indicates further action may be taken against sites that remain under-owned, though the message centre post stops short of naming a hard deletion date.
"Sites without a resilient ownership structure are more likely to become orphaned, lose institutional knowledge, and create compliance gaps when the sole owner leaves the organisation," reads the rationale section of the announcement.
That framing lines up with a pattern most SharePoint admins already recognise. A site gets provisioned for a single project lead, that person changes roles or leaves, and nobody remembers to reassign ownership. The site keeps running, files keep accumulating, and the only person who could grant new access, review permissions, or make a call on archiving it is gone.
Who Gets Caught by the Retroactive Scope
| Site profile | Typical exposure |
|---|---|
| Sites older than 3 years | High: provisioned before shared-ownership norms were common practice |
| Project or client sites | High: often owned by a single account manager or consultant |
| Sites created via self-service provisioning | Medium: creator is automatically the sole owner unless a second is added manually |
| Sites created through a governed request process | Low: many governance templates already require a second owner at creation |
Tenants that never enforced a second-owner rule at creation time are the ones with the longest remediation list. Rather than adding owners one site at a time as the admin centre flags them, it is faster to pull a complete inventory up front and work through it in priority order.
Getting Ahead of the Flag
A full site inventory with the current owner listed against each site is the starting point, since the admin centre's new column only tells you a site is short an owner, not who the logical second owner should be. ShareMaster's Report Master exports exactly that: every site with its owner, storage, and last activity, to Excel, so remediation can be assigned by department or business unit instead of chased one admin-centre page at a time. The guide to finding sites without an owner walks through building that list and closing the gaps before the second phase of enforcement is scheduled.
For a fuller reference on what SharePoint expects from site ownership generally, including what happens when the sole owner's account is disabled, see the site ownership requirements reference.
Sources: Microsoft 365 Message Center MC1402118 (merill.net archive); Microsoft Learn: Manage site collection administrators.