Microsoft kills Office Online Server, encourages businesses to switch to Microsoft 365

Microsoft has just announced that it will officially stop supporting Office Online Server at the end of 2026, marking the end of one of the Office versions specifically for businesses using on-premises systems.

What is Office Online Server?

Office Online Server (OOS) is a version that allows businesses to deploy Office applications on internal servers, instead of having to use Microsoft's cloud infrastructure.

Thanks to this, users in the same system can still access Word, Excel, PowerPoint, OneNote. right on the web browser, similar to regular Office Online, but data is stored internally, ensuring control and security according to business requirements.

The reason Microsoft 'killed' Office Online Server

According to Microsoft, this decision is to 'modernize the productivity experience' and focus on cloud-first solutions. Therefore, Office Online Server is no longer suitable for the new development direction and will be discontinued from December 31, 2026.

After this date, OOS will no longer receive security patches, bug fixes, technical support, or standards compliance guarantees. Microsoft recommends that affected organizations migrate to Microsoft 365 – a platform designed in line with its 'cloud-first' vision.

Impact and alternatives

Microsoft says the end of support for OOS does not affect other products such as Exchange Server Subscription Edition or SharePoint Server Subscription Edition. Businesses using these products can still use Microsoft 365 Apps for Enterprise or Office LTSC 2024 as desktop applications to view and edit documents stored on internal servers.

However, for organizations that use Office Online Server to save and process Excel spreadsheets in Power BI Report Server, this feature will no longer be available after OOS is retired.
Microsoft offers two alternatives:

Open the file using the Excel desktop application, or
Migrate to the Power BI Service platform.

Why switch to Microsoft 365?

Migrating to Microsoft 365 brings many clear benefits to businesses, including:

Real-time collaboration on the same document.
Automatic updates and continuous security patches.
Deep integration with other tools like Teams, Outlook, SharePoint Online.
Complies with global data and security standards.
Access the Microsoft 365 Copilot AI tool – a cloud-exclusive feature.

Although the end of support is still more than a year away, Microsoft recommends that businesses start their transition roadmap now, as data migration and system restructuring can be time-consuming and resource-intensive.