Microsoft 365 Copilot Cannot Open Referenced Document: Fix

When you ask Copilot in Microsoft 365 apps to summarize or analyze a document, it may respond with an error stating it cannot open the referenced document. This problem typically occurs because Copilot lacks the necessary permissions to access the file or because the document is stored in a location that Copilot cannot reach. In some cases, the document format is not supported by Copilot. This article explains the root causes of this access failure and provides step-by-step fixes to restore Copilot’s ability to read your documents.

Why Copilot Cannot Open Referenced Documents

Copilot accesses documents through Microsoft Graph, which enforces the same permissions that apply in SharePoint, OneDrive, and Teams. If the signed-in user does not have at least Read permission on the document, Copilot will fail to open it. Additionally, documents stored outside the Microsoft 365 ecosystem, such as on a local hard drive or a third-party cloud service, are not accessible to Copilot. The document must be stored in OneDrive, SharePoint, or Teams file storage. Another common cause is that the document is in a format Copilot does not support. Copilot works with Word, PowerPoint, Excel, PDF, plain text, and HTML files. Files with extensions like .odt, .pages, or .rtf will trigger the cannot open error. Finally, if the document is encrypted with Microsoft Information Protection sensitivity labels and the user does not have the required usage rights, Copilot will be blocked from reading the content.

Permission Scope and Inheritance

Permissions in SharePoint and OneDrive can be inherited from parent sites or folders. A document that appears accessible in the browser may still be blocked for Copilot if the user’s token does not include the specific site collection or folder permission. Copilot uses delegated permissions, meaning it operates under the context of the signed-in user. If the user is a guest in the tenant where the document resides, Copilot may not be able to open the file even if the user can view it manually.

Steps to Fix Copilot Document Access Errors

Follow these steps in order. After each step, test Copilot again by asking it to summarize the document. If the issue persists, proceed to the next step.

1. Verify Copilot license assignment
   Open the Microsoft 365 admin center and go to Billing > Licenses. Confirm that the user account running Copilot has a Copilot for Microsoft 365 license assigned. Without this license, Copilot will not attempt to open any document.
2. Check document storage location
   Open the document in your browser. The URL must contain sharepoint.com, my.sharepoint.com, or teams.microsoft.com. If the document is stored on a local drive or a non-Microsoft cloud service, move it to OneDrive or SharePoint. Then reference the document again in your Copilot prompt.
3. Grant explicit Read permission
   SharePoint or OneDrive: Right-click the document and select Manage access. Click the ellipsis (…) next to the user name and ensure the permission level is at least Read. If the user is not listed, click Add people, enter the user’s email, and assign Read permission.
4. Remove sensitivity label restrictions
   If the document has a sensitivity label that restricts access to specific users or groups, open the document in the desktop app. Go to Home > Sensitivity and select a label that allows broader access, such as General. Save the document and try Copilot again.
5. Convert unsupported file formats
   If the document is in a format like .odt, .pages, .rtf, or .csv, open it in the corresponding application and save a copy as .docx for Word documents, .xlsx for spreadsheets, or .pdf for fixed-layout documents. Upload the converted file to OneDrive or SharePoint.
6. Clear Copilot cache and sign out
   In the Microsoft 365 app, go to Settings > Accounts > Sign out of all accounts. Close the app, restart it, and sign in again. This refreshes the authentication token and may resolve permission caching issues.
7. Enable Copilot in the tenant
   As a global admin, go to the Microsoft 365 admin center > Settings > Org settings > Copilot. Ensure the toggle for Allow Copilot to access organizational content is turned on. This setting controls whether Copilot can read documents from SharePoint and OneDrive.

If Copilot Still Has Issues After the Main Fix

Copilot Returns Error Even After Granting Permissions

If you have granted Read permission but Copilot still cannot open the document, the issue may be with site-level permissions. Go to the SharePoint site where the document is stored. Click Settings > Site permissions. Ensure the user is not blocked by a sharing restriction or a site-level access policy. If the site is set to private, add the user as a site member with Read access.

Document Opens in Browser but Not in Copilot

This can happen when the document is stored in a SharePoint site that has custom scripting disabled or that uses an older permission model. Check the site collection admin settings. Go to the SharePoint admin center > Sites > Active sites. Select the site, click Policies, and ensure that the site is not configured to block Microsoft Graph API access. If it is, change the policy to allow API access.

Copilot Cannot Open a Document in Microsoft Teams

Files shared in Teams channels are stored in the underlying SharePoint site for the team. The user must have access to that SharePoint site. Open the Files tab in the Teams channel, find the document, and click the ellipsis (…) > Open in SharePoint. Check the permissions on the SharePoint document library. If the user is a guest in the tenant, they may need explicit access to the library.

Item	Supported Storage	Unsupported Storage
Description	Locations Copilot can access	Locations that cause the cannot open error
OneDrive for Business	Yes	No
SharePoint Online	Yes	No
Microsoft Teams Files tab	Yes	No
Local hard drive	No	Yes
Google Drive or Dropbox	No	Yes
Network file share	No	Yes

Copilot cannot open documents stored outside OneDrive, SharePoint, or Teams. If you reference a local or third-party file, move it to a supported location and update your prompt.

You can now diagnose and resolve the Copilot cannot open referenced document error by checking permissions, storage location, file format, and tenant settings. Test the fix by asking Copilot to summarize the document after each step. For recurring issues, verify that the user account is not a guest in the tenant where the document is stored. As an advanced tip, use the Microsoft Graph Explorer to test the user’s token permissions by running a GET request on the document’s driveItem endpoint. This will reveal whether the token has the necessary Files.Read.All or Sites.Read.All scope.