Copilot Chat Conversation History Missing: Fix

You open the Copilot pane in Microsoft 365 and your previous chat threads are gone. The conversation history panel shows a blank list or only the current session. This problem typically occurs after a Microsoft 365 update, a license re-assignment, or when the Copilot service experiences a temporary data sync failure. This article explains the root cause of missing history, provides a step-by-step fix to restore it, and covers related failures like disappearing messages mid-conversation.

Why Copilot Conversation History Disappears

Copilot chat history is stored in the Microsoft Graph and linked to your user profile through an Azure AD token. When the token expires or becomes corrupted, the Copilot pane cannot enumerate past conversations. A second common cause is a license provisioning delay. After an admin assigns the Copilot license, it can take up to 24 hours for the service to create the user-specific storage container. During that window, the history tab returns empty results. A third cause is a local cache mismatch. The Copilot pane caches a summary of your chat list. If the cache becomes out of sync with the server, the pane displays an empty list even though the server still holds the data.

Token Expiration and Refresh

Microsoft 365 uses OAuth 2.0 tokens that expire every 90 minutes by default. When the Copilot pane cannot refresh the token silently, it reverts to a guest state and shows only the current session. This is not a data loss event. The history remains on the server and becomes visible after a successful token refresh.

License Provisioning Delay

The Copilot license must be assigned to a user and then provisioned by the Copilot backend. Provisioning creates a dedicated chat history store. If you check history immediately after license assignment, the store may not exist yet. The delay can last from a few minutes to 24 hours depending on tenant load.

Steps to Restore Missing Copilot Chat History

Follow these steps in order. Stop after the step that restores your history. If a step does not fix the problem, move to the next one.

Method 1: Refresh the Copilot Pane

1. Open the Copilot pane
   In any Microsoft 365 app, click the Copilot icon on the ribbon or press Alt+Space to open the pane.
2. Click the History tab
   The tab is located at the top of the pane, between the Compose and Settings tabs.
3. Click the Refresh button
   The refresh icon is a circular arrow at the top-right of the history list. Clicking it sends a new Graph request for your conversation list.

Method 2: Sign Out and Sign Back In

1. Open the Copilot pane
   Click the Copilot icon in the app ribbon.
2. Click your profile picture
   Your profile picture is in the top-right corner of the pane.
3. Select Sign out
   Confirm the sign-out prompt. The pane resets to a blank state.
4. Sign back in
   Click the Sign in button and enter your Microsoft 365 credentials. A new token is issued and the pane re-fetches your history from the server.

Method 3: Clear Stale Authentication Tokens

1. Open Windows Credential Manager
   Press the Windows key, type Credential Manager, and select the app from the results.
2. Click Windows Credentials
   This tab shows all stored Windows and Microsoft 365 credentials.
3. Scroll to the MicrosoftOffice16 section
   Look for entries that start with MicrosoftOffice16_Data:ADAL:. These are the Active Directory Authentication Library tokens used by Copilot.
4. Expand each ADAL entry and click Remove
   Remove all entries that contain your work email address. Do not remove entries for other accounts.
5. Restart the Microsoft 365 app
   Close and reopen Word, Excel, or Outlook. The app requests a fresh token from Azure AD on startup.

Method 4: Re-Apply the Copilot License

1. Open the Microsoft 365 admin center
   Go to admin.microsoft.com and sign in as a global or license admin.
2. Navigate to Users > Active users
   Select the user whose Copilot history is missing.
3. Click the Licenses and apps tab
   Scroll to the Copilot license section.
4. Uncheck the Copilot license and save
   Wait 60 seconds.
5. Re-check the Copilot license and save
   This triggers a fresh provisioning request. The user may need to sign out and sign back in to see the history.

If Copilot Still Has Issues After the Main Fix

Copilot Shows Only the Current Session After Refresh

If the history list remains empty after a refresh, the Graph endpoint may be throttling your account. Wait 15 minutes and try the refresh again. Throttling usually clears automatically. You can also check the Microsoft 365 Service Health dashboard for any ongoing Copilot incidents.

Conversation History Is Empty on One Device but Not Another

This indicates a local cache corruption on the affected device. Clear the Microsoft 365 app cache by navigating to %localappdata%\Microsoft\Office\16.0\OfficeFileCache and deleting all files inside the folder. Restart the app and open the Copilot pane.

Copilot History Disappears After a Microsoft 365 Update

Some updates reset the local Copilot cache. After the update, the pane may take up to 10 minutes to rebuild the history list from the server. Leave the pane open for 10 minutes without interacting. The history should populate automatically.

Copilot Chat History Missing: Local vs Server Behavior

Item	Local Device Behavior	Server Behavior
History visibility after token refresh	Requires manual refresh or sign-out	All history remains intact
Cache corruption	Shows empty list even if server has data	No impact
License provisioning delay	Shows blank history for up to 24 hours	Storage container not yet created
Throttling	Returns empty Graph response for 15-30 minutes	Limits request rate, no data loss

You now know the four main causes of missing Copilot chat history and the exact steps to restore it. Start with a pane refresh and a sign-out cycle. If that does not work, clear the ADAL tokens in Credential Manager. As a final step, ask your admin to re-apply the Copilot license. For ongoing reliability, set a calendar reminder to check the Microsoft 365 Service Health dashboard once a week for Copilot-related incidents.