You open Copilot in Word, Excel, or the Microsoft 365 app and see a red error message: Reference Not Found. The error stops Copilot from generating any response. This happens when Copilot cannot locate the data source or document it needs to ground its answer. In most cases, the root cause is a missing or misconfigured Microsoft Graph connector, a broken SharePoint file link, or a permission gap on the referenced content. This article explains why the error occurs and provides the exact steps to resolve it across Microsoft 365 apps.
Key Takeaways: Fixing the Reference Not Found Error in Copilot
- Microsoft 365 admin center > Copilot > Data sources: Verify that the referenced Graph connector or SharePoint site is listed and active.
- SharePoint document link check: Ensure the file URL in the Copilot prompt points to an existing, non-deleted file with proper sharing permissions.
- Copilot settings > Plugins: Disable and re-enable the Microsoft Graph connector to refresh its connection to the data source.
Why Copilot Shows Reference Not Found
The Reference Not Found error occurs when Copilot tries to read a specific data source but cannot access it. Copilot relies on Microsoft Graph connectors, SharePoint file links, or Microsoft 365 data sources to generate grounded responses. If any of these sources are missing, misconfigured, or blocked, Copilot returns the error instead of a response.
The most common root causes are:
Missing or Disabled Graph Connector
Microsoft Graph connectors bring external data into Copilot. If an admin deletes or disables the connector that the prompt references, Copilot cannot find the data. This is the leading cause in enterprise environments where connectors are managed centrally.
Broken SharePoint or OneDrive File Link
When you ask Copilot to summarize a specific document, it uses the file URL to access the content. If the file was moved, renamed, or deleted, Copilot cannot resolve the reference. The same happens if the file is stored in a site that Copilot does not have permission to read.
Permission or License Gaps
Copilot requires a valid Microsoft 365 Copilot license and the correct permissions on the data source. If your account lacks read access to the SharePoint site, the Graph connector, or the document library, Copilot returns the Reference Not Found error.
Steps to Resolve the Reference Not Found Error
Follow these steps in order. Test Copilot after each step to see if the error clears.
Step 1: Check the Data Source in the Microsoft 365 Admin Center
- Open the Microsoft 365 admin center
Go to admin.microsoft.com and sign in with a Global Admin or SharePoint Admin account. - Navigate to Copilot settings
Select Settings > Org settings > Copilot. This page lists all active data sources. - Verify the Graph connector status
Under Data sources, look for the connector name that matches the reference in your prompt. If the connector shows as Disabled or Error, select it and click Enable or Reauthorize. - Test Copilot again
Return to Copilot in Word or the Microsoft 365 app and repeat the prompt that caused the error.
Step 2: Verify the SharePoint File Link
- Copy the exact file URL from your prompt
If you typed a file path or pasted a link, copy it exactly. - Open the link in a browser
Paste the URL into a new browser tab. If the file opens, the link is valid. If you see a 404 error or access denied, the file is missing or permissions are wrong. - Fix the file location or permissions
If the file was moved, locate it in SharePoint or OneDrive and copy the new link. If permissions are missing, ask the file owner to grant you at least read access. - Update the prompt with the correct link
In Copilot, start a new conversation and paste the corrected file URL.
Step 3: Refresh the Graph Connector Connection
- Open Copilot settings in the app
In Microsoft 365, select the Copilot icon and click the gear icon to open Copilot settings. - Go to Plugins
Select Plugins from the left menu. This page shows all active plugins including Graph connectors. - Disable and re-enable the connector
Find the connector that matches your data source. Toggle it off, wait 10 seconds, then toggle it back on. This forces Copilot to reauthenticate the connection. - Restart the Microsoft 365 app
Close and reopen Word, Excel, or the Microsoft 365 app. Test the prompt again.
Step 4: Confirm License and Permissions
- Check your Copilot license
In the Microsoft 365 admin center, go to Users > Active users, select your account, and verify that a Copilot license is assigned under Licenses and apps. - Verify SharePoint site permissions
If the referenced file is on a SharePoint site, confirm that your account has at least Read permission on the site. The site owner can add you via Site permissions > Share site. - Check Graph connector permissions
For external data sources, the connector must be configured to allow your account access. Contact your Microsoft 365 admin to review connector permissions in the admin center under Settings > Org settings > Copilot > Data sources.
If Copilot Still Shows the Error After the Main Fix
Copilot Returns Reference Not Found on Every Prompt
If the error appears even when you do not reference a specific file or connector, the issue is likely a corrupted Copilot cache or a service outage. Clear the Copilot cache by signing out of Microsoft 365, closing all Office apps, and signing back in. If the error persists, check the Microsoft 365 Service Health dashboard at admin.microsoft.com > Health > Service health for any active incidents affecting Copilot.
Copilot Shows the Error Only on External Data Sources
This indicates a problem with the Microsoft Graph connector itself. The connector may have been deleted or its API key may have expired. Ask your admin to go to Settings > Org settings > Copilot > Data sources and click Edit next to the connector. The admin can reauthorize the connection or delete and recreate it. After the connector is fixed, disable and re-enable the plugin in Copilot settings as described in Step 3.
Copilot Shows the Error After a SharePoint File Rename
If you rename a file after Copilot references it, the original link becomes invalid. Copilot does not automatically update the reference. You must provide the new file URL in your prompt. To avoid this, rename files before you ask Copilot to reference them, or use a SharePoint document library with versioning enabled so the file ID stays the same even after renaming.
Copilot Reference Not Found vs Other Copilot Errors
| Item | Reference Not Found Error | Copilot Unavailable Error |
|---|---|---|
| Root cause | Missing or inaccessible data source | Service outage or license issue |
| Typical fix | Check connector, file link, or permissions | Wait for service restoration or assign license |
| Error message | Reference Not Found | Copilot is not available right now |
| Scope | Specific prompt or data source | All Copilot features |
| Admin action needed | Often yes, to fix connectors or permissions | Sometimes, to check license assignments |
The Reference Not Found error is a data access problem, not a service outage. The steps in this article focus on restoring access to the specific data source Copilot needs.
You can now diagnose and fix the Reference Not Found error in Copilot by checking Graph connectors, file links, and permissions. Start with the data source list in the Microsoft 365 admin center, then verify the file URL in your prompt. If the error persists, refresh the connector plugin in Copilot settings. For recurring issues, ask your admin to review the connector configuration and ensure your account has the correct permissions on all referenced data sources.