SharePoint agents built with the .agent file format have an expiry date, and most site owners have no idea. Microsoft is moving these SharePoint agents to the Microsoft Copilot Agent Builder and the plugin store, and the old files stop working in April 2027. Nothing breaks today, which is exactly why this one is easy to ignore.
This post walks through what Microsoft announced in message center item MC1511052, what changes for your tenant, and how I would handle the upgrade as an admin.
What is changing for SharePoint agents
Microsoft is upgrading the agent experience in SharePoint and OneDrive so that it lines up with the wider Copilot extensibility ecosystem. In practice, SharePoint agents become part of the Copilot app home experiences and the Microsoft plugin registry, the shared catalog where organization-approved and custom plugins are discovered, published and governed.
The change comes in two steps:
- Mid-November 2026: choosing ‘Create an agent’ or ‘New agent’ in SharePoint or OneDrive opens the Microsoft Copilot Agent Builder. New agents land in the plugin store and no longer create .agent files.
- End of March 2027: existing .agent file agents keep working across SharePoint, Teams and the Copilot app until this date. After that they stop.
You do not have to change any .agent file today. You can even keep editing existing ones during the transition period. But the clock is running, and every SharePoint agent that nobody upgrades becomes a support ticket in April.
Rollout timeline
This should be rolling out in mid-November 2026 according to Microsoft, with the second rollout following in spring 2027. There is no preview phase in this message, so both rollouts are general availability.
| Phase | What happens | Timing |
|---|---|---|
| Agent creation and upgrade (General Available) | New agents use Copilot Agent Builder, upgrade options appear | Rollout begins mid-November 2026, expected to complete by early December 2026 |
| .agent files stop working (General Available) | Old format agents stop working in SharePoint, Teams and the Copilot app | Rollout begins early April 2027, expected to complete mid-April 2027 |
Three upgrade paths for your SharePoint agents
Microsoft does not give you a single migration button for all SharePoint agents. The right path depends on what each agent helps users do today.
Use Copilot in SharePoint for site-level questions
If the agent mainly answers questions about the content on one site, you may not need a separate agent at all. Copilot in SharePoint already covers site-level questions and answers.
Convert the .agent file to a skill
When the agent supports a focused task or business outcome that is specific to a site, Microsoft offers a convert-agent-file-to-skill skill in Copilot in SharePoint. The result can use the capabilities of Copilot in SharePoint.
Upgrade to a declarative agent or custom engine agent
If users need a content-grounded, conversational experience across Microsoft 365, upgrade to a declarative agent, or update the custom engine agent you published to the SharePoint channel. In the SharePoint agent builder, an ‘Upgrade to M365 Agent’ button will appear to make this easier.
The Agent Chat web part is also described as coming soon. It lets you place any agent from the plugin store on a SharePoint page with more control over how it shows up.
How to prepare your SharePoint agents step by step
- Find them. Ask site owners who created SharePoint agents in SharePoint or OneDrive. Do not rely on one person’s memory. Microsoft links to guidance on finding and upgrading existing agents in the message.
- Sort them. For each agent, write down the purpose, the site, the owner and the number of users.
- Pick a path. Site Q&A goes to Copilot in SharePoint, a focused task becomes a skill, a cross-app conversation becomes a declarative agent.
- Assign an owner. Every upgraded agent needs a named person who maintains it.
- Test before April. Upgrade in the quiet months, not the week the old format stops.
Admin tips for governing SharePoint agents
The governance story changes with this move. Agent Builder, the Microsoft 365 admin center and Agent 365 become the places where you manage, report on and analyze usage of new and upgraded SharePoint agents. Microsoft also states that Agent 365 provides centralized controls, so review which platform controls apply to your organization.
- Review permissions first. Upgraded agents use SharePoint content and site context for conversational experiences. If a site is overshared, the agent will surface what people can already open. Fix that before you scale agents. My article on SharePoint Copilot credits shows why usage and cost follow the same discipline.
- Understand the data question. Microsoft answers yes to the question of whether the change stores new customer data: upgraded and new agents managed through Agent Builder, the plugin store, Agent 365 and the admin center may use SharePoint content and site context.
- Brief your site owners. They create SharePoint agents, so they need to know that new agents will not be .agent files anymore. If you are also looking at agentic work across apps, read my guide to Copilot Cowork.
- Plan your helpdesk message. A short note in advance beats a surprise in April.
License requirements
This change applies to organizations using agents in SharePoint and OneDrive, which means SharePoint site owners and members who create or manage agents in the .agent format, and the admins responsible for governance, adoption, licensing and support. Microsoft states that Copilot in SharePoint is already available worldwide. Check with your licensing contact which of your users hold a Microsoft 365 Copilot license, because that decides who can build and use agents with Agent Builder. The Microsoft Learn admin guide for agents lists the current requirements.
Why this matters for your organization and your SharePoint agents
I see the same pattern in many tenants when it comes to SharePoint agents. A motivated site owner builds a useful agent in an afternoon, shares it with the team, and then moves to another role. Six months later the SharePoint agent is part of how a department works, but nobody in IT knows it exists. When the format stops working, the department does not call the site owner. They call you.
Upgrading SharePoint agents is not hard. The hard part is knowing which ones you have. That is a governance problem, not a technical one, and the time to solve it is the period between now and March 2027.
What I would do first with your SharePoint agents
Start with an inventory. Even a simple spreadsheet with agent name, site, owner, purpose and chosen upgrade path is enough. Then run one pilot upgrade with a friendly site owner so you learn how the Upgrade button and the skill conversion behave in your tenant before you roll it out to everyone.
The Paul-Take
Nothing breaks today, and that is exactly the danger. Agents created by enthusiastic site owners over the past year are rarely documented, and nobody owns the upgrade. Use the quiet months until March to find them, decide per agent which path fits, and put someone in charge. Waiting until April means your users find out from a broken agent, not from you.
This should be rolling out in mid-November 2026 (agent creation and upgrade) and early April 2027 (.agent files stop working) according to Microsoft. Do you know how many SharePoint agents live in your tenant right now? Drop a comment, I am curious how many surprises people find.
MVP Reference List
- Message center: MC1511052, Upcoming changes to Agents in SharePoint and OneDrive (published 16 October 2026)
- Related message center items referenced by Microsoft: MC1479277 (Copilot app home experiences) and MC1484008 (Microsoft plugin registry)
- Microsoft 365 Roadmap: Microsoft 365 Roadmap (the message does not list a specific Roadmap ID)
- Microsoft Learn: Agents admin guide for Microsoft 365
- Microsoft Learn: Agent Builder
- Microsoft Learn: Build and reuse declarative agents
- Microsoft Learn: Get started with Copilot in SharePoint