Microsoft has quietly changed how Microsoft 365 Copilot works on mobile devices, and the update is already frustrating users. According to Windows Latest, on Android and iOS, the app no longer opens local documents directly. Instead, it uploads files to OneDrive and routes everything through Copilot chat.
This shift marks a major change for an app many people still use as a simple document viewer.
Copilot chat replaces the traditional document viewer
Earlier versions of the app opened Word, Excel, and PowerPoint files locally with minimal friction. That behavior has now changed. When users tap a local file—such as a document received on WhatsApp—the app launches Copilot chat instead of a normal preview.
Microsoft positions this design as a productivity upgrade. Copilot offers instant summaries and conversational insights. In practice, the update adds extra steps and removes the option to simply read a file.
Local files now upload to OneDrive automatically
When a user opens a local file, Microsoft 365 Copilot first uploads it to OneDrive. Only after the upload completes does Copilot attempt to analyze and summarize the document.
If the upload fails or Copilot cannot process the file, the document may not open at all. In some cases, Copilot pulls references from unrelated older files stored in OneDrive, leaving users unable to access the document they actually tapped.
This behavior affects files that are not already synced with OneDrive. Documents that already live in the cloud still open more reliably.
The document viewer still exists, but it’s hidden
Microsoft has not removed the traditional viewer entirely. The app now hides it inside Copilot’s References section. Users must enter Copilot chat first, wait for processing, and then navigate deeper to find the actual document preview.
If Copilot fails to understand the file, the viewer may never appear. At that point, users must manually upload the file to OneDrive and search for it again inside the app.
Why Users Are Unhappy With the Copilot Mobile OneDrive Upload Change
The change turns Microsoft 365 Copilot into a Copilot-first app rather than a document viewer. Users who only want to read a file now face forced uploads, AI processing delays, and occasional failures.
The update also raises privacy concerns. Local documents now move to the cloud by default, even when users expect a simple offline preview. For business users and professionals, this behavior introduces unnecessary risk and friction.
Microsoft now recommends using standalone apps like Word, Excel, and PowerPoint for straightforward file viewing on mobile. Those apps still open local documents without routing them through Copilot.
That recommendation alone highlights the problem. An app that once handled basic viewing tasks now pushes users away unless they fully embrace Copilot and cloud syncing.
Whether users accept this Copilot-first approach will depend on future updates. For now, Microsoft 365 Copilot on mobile feels less like a productivity tool and more like an AI gateway that gets in the way of basic document access.
