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Planner Likes to be Connected
Planner is a browser-based app. A mobile app is available but not a desktop app. In short, Planner expects you to be online to work with its plans and tasks. The same is true of Teams if you work with Planner data through its Tasks app or a channel tab.
Although the Planner iOS client has read-only capability when offline, I’ve never attempted to work with the Planner browser client without a network connection. It seemed like a fool’s errand to try, and it was only by accident that I came to be working through a set of new Office 365 notifications imported into Planner through the synchronization with the Office 365 admin center when our ISP link failed. When I updated a task to move it to a different bucket, Planner noticed that it was offline and displayed the message shown in Figure 1.

Not Like Outlook
Many products include some form of offline capability. Usually data is cached locally to allow the app to continue working during a network outage. The app’s functionality might be reduced, but at least users can get some work done. Outlook is an example of a product designed with offline capability in mind. For almost 20 years (since the introduction of “drizzle-mode synchronization” in Outlook 2003), it’s been possible to have a complete copy of user mailboxes offline and to be able to work with the mailbox contents when no network is available. When the network link is restored, Outlook synchronizes any changes made offline and downloads new information available on the server.
Planner can detect network changes, caches information about tasks and plan structure (like buckets). When the network connection is available, Planner synchronizes the changes made offline to the server. However, Planner is no Outlook.
What Planner Can Do Offline
After testing with both the Edge (Chromium) and Brave browsers on Windows, it seems that you can perform the following operations when working offline:
- Add a new task to a plan.
- Update task properties like progress (not started, completed), start and due dates, notes, comments, and priority.
- Add or remove a web link or file attachment.
- Add or remove checklist items for a task.
- Move tasks between buckets.
- Assign a task to team members.
You cannot:
- Start Planner when offline.
- Add a SharePoint item to a task.
- Create a new plan for an existing group or with a new group.
Using the cached data, Planner Graphs and Schedule View are available when offline.
Occasionally Planner won’t be able to update an item (Figure 2) and you’ll have to wait until the network is available before proceeding.

A Good Start
Planner’s offline capability is basic. It’s a version one implementation that should improve over time. Whether it’s enough to keep people working during extended network outages remains to be seen, but it’s enough to handle transient connectivity drops. It’s just a pity that the Planner developers say nothing when they introduce a new feature like this – not in their blog, an Office 365 notification, or in a Microsoft 365 roadmap item (only 10 items are listed for Planner).
Discovering stuff like this sometimes can only be done through ongoing use of Office 365 apps. The Office 365 for IT Pros eBook team uses Office 365 to create the book; it is based on real-life experience, which is why its content is so valuable.
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