You inherit a tenant with 600 sites. Nobody can tell you, off the top of their head, which of those sites still has a living, working owner attached to it. That gap is the one this guide closes.
Ownership is one of the quietest failure points in SharePoint governance. A site does not stop working when its owner leaves the company. Files stay accessible, permissions stay in place, and nothing visibly breaks. What breaks is accountability: nobody can approve a new access request, decide whether the site should be archived, or answer for what is stored there when an audit asks. This guide covers how to find every site missing an owner, and how to close the gap methodically rather than one admin-centre click at a time.
Why This Is Easy to Miss
Self-service site creation is convenient, and that convenience has a cost. When a user creates a team site or a communication site, they become the sole owner by default. Unless someone deliberately adds a second owner, that site is exactly one resignation away from having none at all. Multiply that across a few years of organic growth and a mid-size tenant can easily be carrying dozens of ownerless sites without a single alert ever firing.
Sites connected to a Microsoft 365 group have a related but distinct problem: group ownership and site ownership can drift apart. A group can lose its last owner in Entra ID while the underlying SharePoint site collection administrator field still shows a name, technically populated but pointing at an account that no longer has group management rights.
What Counts as "No Owner" in Practice
Before you start exporting reports, it helps to define the categories you are actually hunting for, since "no owner" covers a few different situations:
- Truly empty: the owner or site collection administrator field is blank.
- Ghost owner: a name is listed, but the account has been disabled or removed from the directory.
- Single point of failure: exactly one active owner exists, with no backup.
- Role mismatch: the listed owner has left the team or department the site actually serves, even though the account is still active elsewhere in the tenant.
All four are worth catching, though the first two are the most urgent, since they represent sites where literally nobody with authority can act today.
Step 1: Check What the Admin Centre Shows You
Start in the Microsoft 365 admin centre. Under Admin centres, open SharePoint, then Sites, then Active sites. The list has a Primary admin column, and selecting a site opens a details panel whose Membership tab shows its site admins and, for a group-connected site, its group owners. That is fine for spot-checks, but the list names one primary admin per site and does not count owners, so a site whose only owner has left looks exactly like a healthy one until you open it.
When the admin centre view is enough
If your tenant has fewer than about thirty sites, clicking through each one individually is realistic. Beyond that, it becomes the kind of task that gets started and never finished, which is exactly how ownerless sites accumulate in the first place.
Step 2: Export the Site List, or Run an Ownership Policy Report
For anything larger than a small tenant, a bulk export beats manual clicking. On the Active sites page, select Export on the command bar. You get the current view as a CSV that opens in Excel, with the primary admin, storage used and last activity for every site, which turns a click-through exercise into a filter.
If your tenant has SharePoint Advanced Management (it comes with Microsoft 365 Copilot licences), there is a better source. Under Policies > Site lifecycle management, create a site ownership policy, set the minimum owner count to two and run it in simulation mode. The downloadable report lists every site in scope that falls short, with the number and email addresses of its owners and admins, its last activity date and its storage used. OneDrive, root, home and app catalog sites are outside its scope.
Step 3: Filter for the Gaps
With the export in hand, filter the Primary admin column (or the policy report's owner and admin counts) for blanks and zeros first. That gives you the truly empty cases. Next, cross-reference the remaining owner names against your directory or HR system to catch ghost owners, accounts that are technically listed but no longer active in the organisation. This second pass takes longer than the blank-cell filter but usually turns up more sites than the first pass alone.
| Filter pass | What it catches | Typical effort |
|---|---|---|
| Blank primary admin, or zero owners in the policy report | Sites with no owner listed at all | Minutes, one filter |
| Owner cross-referenced against directory | Ghost owners: listed but no longer active | Longer, needs a directory export to compare against |
| Single-owner sites (an owner count of one in the policy report) | Sites at risk of becoming ownerless next | A follow-up pass once the urgent gaps are closed |
Step 4: Prioritise Before You Start Assigning Owners
Not every flagged site deserves the same urgency. Sort your filtered list by storage used and last activity together. A site with recent uploads and no owner needs attention this week. A site with no owner and no activity in over a year is a better candidate for an archive-or-delete conversation than for hunting down a new owner who may not even remember the site exists.
- Active, unowned sites: assign a new owner immediately.
- Active, single-owner sites: add a second owner as a safeguard.
- Dormant, unowned sites: route to an archive or deletion decision instead of an ownership fix.
Step 5: Assign the Owners
In the SharePoint admin centre, select the site on the Active sites page and choose Membership. For a standalone site, add a new site admin. For a group-connected site, add the new person as a group owner on the same panel, since the group owner list is what governs site-level administrative rights for that site type. Where your organisation uses a request or approval workflow for ownership changes, route the assignment through that process so there is a record of who approved it.
Step 6: Confirm the Fix
Export the Active sites list again, or re-run the ownership policy report, once remediation is done. Compare it against your original flagged list line by line. For a single site, ShareMaster's Security Matrix report lists who sits in the site's Owners group and what permission level each principal holds, which is a quick way to check a fix landed on the right group. This closing pass matters because it is easy for an ownership change to be applied at the wrong level, added as a member instead of an owner, for instance, and the only reliable way to catch that is to check the export, not to trust that the change went through as intended.
Frequently Asked Questions
Why does a SharePoint site end up with no owner?
Most commonly, the original owner leaves the organisation or changes roles and nobody reassigns the site before their account is disabled. Self-service site creation is another common cause, since the creator becomes the sole owner automatically.
Can I tell which sites lack an owner from the SharePoint admin centre alone?
The Active sites list shows each site's primary admin and exports to CSV, but it does not count owners or flag ownerless sites. A site ownership policy in SharePoint Advanced Management produces that report directly; without it, export the list and cross-check the names against your directory.
What happens if a site is left without any owner indefinitely?
The site keeps functioning for existing members, but nobody can approve new access requests, review permissions, or make governance decisions about its future.
Should every SharePoint site have more than one owner?
A second owner is widely recommended as good governance practice, since it removes the single point of failure created when the sole owner leaves or becomes unreachable.
See ShareMaster's permission reports
For the underlying rules Microsoft applies to site ownership, and how a site ownership policy can require a minimum of two owners, see the site ownership requirements reference.