Office Online Server (OOS) is being deprecated
Office Online Server Retirement: What It Means for Power BI Report Server Users — And Why It’s Time to Plan for the Future
Microsoft has officially announced the retirement of Office Online Server (OOS) by December 31, 2026, and while that might sound like a distant milestone, it’s a seismic shift for organizations still running Power BI Report Server (PBIRS) with Excel workbooks hosted on-premises.
If your business relies on PBIRS for Excel rendering or legacy reporting workflows, this announcement isn’t just a note to file — it’s a sign of where the whole Microsoft data ecosystem is heading.
Let’s break down what’s changing, what it means, and why slow-moving industries need to start preparing now.
What’s Changing
Microsoft’s announcement includes three key milestones:
January 2026 — PBIRS will stop allowing new configurations of OOS for hosting Excel workbooks.
November 2026 — PBIRS will stop supporting Excel workbook hosting through OOS entirely.
December 31, 2026 — Office Online Server itself reaches its official end of support.
In short: if you’re using PBIRS + OOS as your Excel hosting solution, that capability will disappear.
Why This Is a Big Deal for On-Prem Power BI
Retiring OOS is more than a technical update — it's a strategic marker. OOS has always been the behind-the-scenes engine that allowed PBIRS to render Excel files. With that gone, the direction is clear:
On-prem Power BI is not where Microsoft is investing for long-term innovation.
The cloud-first strategy has been obvious for years, but this is one of the clearest signals yet that the on-prem reporting stack’s future is limited. Organizations can continue running PBIRS for paginated reports and Power BI visuals, but the feature gap is getting wider.
The Cloud Is Where the Innovation Lives
If you compare PBIRS with the Power BI Service (and now Microsoft Fabric), the difference isn’t subtle:
AI-driven experiences
Fabric OneLake + Direct Lake
Centralized governance & lineage
Semantic model sharing
Git integration & deployment pipelines
Automated refresh at scale
Truly modern Excel integration
And dozens more improvements every quarter
None of these are coming to PBIRS. The innovation curve is skyrocketing in the cloud.
This OOS retirement is one more nudge from Microsoft saying, “It’s time.”
Slow-Moving Industries Need to Act Early
Some industries simply move at a slower pace — and they know it. Banking, government, healthcare, and other regulated environments often take years to make platform changes.
For these organizations, 2026 is right around the corner.
Waiting until late 2026 to react means:
rushed migrations
increased security risk
unsupported infrastructure
expensive last-minute consulting
internal teams scrambling
The organizations that win are the ones that treat this as a two-year runway, not a two-year delay.
Why This Is Actually a Good Move
Despite the disruption, this is a healthy step for the ecosystem.
It simplifies the architecture.
It removes a legacy dependency that wasn’t evolving.
It pushes organizations toward modern, secure, cloud-first reporting experiences.
And it reduces the operational drag caused by on-prem services that simply can’t keep pace.
From a consulting and technology strategy perspective, this helps teams finally get the support they need to modernize their BI platforms.
What Organizations Should Do Next
If you’re running PBIRS today, here’s where to start:
1. Inventory your PBIRS workloads
Which reports use OOS?
Which Excel workbooks are actively used?
Which teams rely on on-prem reporting workflows?
2. Define a “stay or go” plan
Some reports stay on-prem.
Some move to Power BI Service.
Some should move to Fabric entirely.
3. Modernize Excel-driven workflows
Many organizations use PBIRS to host Excel files simply because “that’s how we’ve always done it.”
This is the perfect time to rethink:
approvals
refresh cycles
data governance
workbook automation
4. Build a migration roadmap
Most organizations need 12–24 months to execute a smooth transition.
That means starting now — not in 2026.
5. Communicate early with stakeholders
Executives, auditors, compliance teams, and IT leadership all care about timelines.
This is your opportunity to frame a proactive modernization initiative rather than a reactive fire drill.
Final Thoughts
Microsoft retiring Office Online Server is more than a product lifecycle update — it’s a wake-up call for any organization still relying on on-prem Power BI Report Server for Excel hosting. The world is moving to the cloud, the innovation is happening in the cloud, and the organizations that start preparing today will be the ones avoiding disruption tomorrow.
If your team is unsure where to start, I help companies build practical, cost-conscious roadmaps to modernize their Power BI environment — whether that means staying hybrid, moving to Fabric, or adopting Power BI Service with strong governance.
