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How to Change the Primary SharePoint Online Administrator via API

Aamir Naveed Akram Oct 21, 2026 870 views

Question details

The user needs to set a specific user as the primary site collection administrator or owner in SharePoint Online using an API endpoint.

How to Change the Primary SharePoint Online Administrator via API

Product: SharePoint Online
Device & OS: not provided
Scenario: Automating the assignment of a primary site collection administrator using an API within a Power Automate workflow.
Observed behavior: Setting the IsSiteAdmin property to true only adds the user as a secondary administrator. The exact endpoint and request body required to assign a user as the primary owner remain unclear.

Before you start

Ensure you have Global Administrator or SharePoint Administrator rights in your tenant, and that your API application has been granted the necessary Microsoft Graph or SharePoint administrative permissions.

Solution 1Recommended

Use Microsoft Graph API for Administrator Management

Microsoft Graph is the modern, recommended standard for managing Microsoft 365 groups and SharePoint Online site administration permissions.

Since legacy REST endpoints often behave differently in modern SharePoint Online environments, Microsoft Graph provides dedicated endpoints for modifying Group owners and Site administrators.

Identify the target site or group

Determine whether the SharePoint site is group-connected (Microsoft 365 Group) or a standalone communication/team site. This dictates which Graph endpoint you must call.

Construct the Microsoft Graph HTTP request

Use the Microsoft Graph API endpoint for Groups (e.g., POST /groups/{id}/owners/$ref) to add a user as an owner. The request body must contain the user's directory object URI.

Execute the request in Power Automate

Use the 'Send an HTTP request' action in Power Automate, configuring it to target Microsoft Graph with the correct authentication headers and JSON payload.

Use Microsoft Graph API for Administrator Management

API Documentation: Always consult the latest Microsoft Graph API documentation, as endpoints and supported methods for site management are frequently updated.

Solution 2

Seek Specialized Guidance in the Power Platform Community

Since the automation relies on Power Automate, leveraging specialized community resources is the fastest way to obtain exact JSON payloads.

Solution 3

Test the On-Premises REST API Endpoint with Caution

You can explore the legacy /_api/site/owner endpoint, though it may not be fully supported in modern SharePoint Online architectures.

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Frequently Asked Questions

Does setting the IsSiteAdmin property make someone a primary administrator?

No. Setting IsSiteAdmin to true typically adds the user to the Site Collection Administrators group as an additional (secondary) administrator, rather than replacing or setting them as the singular primary owner.

Can I reliably use the /_api/site/owner REST endpoint in SharePoint Online?

While this endpoint was standard for on-premises SharePoint, its functionality in modern SharePoint Online is often limited or unsupported. Microsoft Graph is the recommended modern alternative for managing ownership.

Where can I find specific JSON payloads for Power Automate HTTP actions?

The best resources for up-to-date, tested JSON payloads and HTTP action configurations are the official Microsoft Power Platform Community forums and Microsoft Q&A.

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