after copilot update, i have one large chat thread that will not load

Export the Copilot activity history immediately, then use the personal-account or work/school-account recovery path below because Microsoft provides no user-side repair for one thread that remains listed but cannot open.

1. Preserve what can still be retrieved

For a personal Microsoft account:

1. Sign in to the Microsoft privacy dashboard with the same account used in Copilot.
2. Go to Privacy → Empower your productivity → Copilot → Your Copilot app activity history.
3. Choose the applicable category:
   • Copilot apps → Export all activity history, or
   • Copilot in Microsoft 365 apps → Export all Copilot Chat activity history.
4. Save and inspect the downloaded CSV file for the prompts and responses from the affected conversation. Microsoft defines activity history as what you entered and Copilot’s responses. ^1^

The CSV is an activity-history export, not an interactive chat backup. Do not assume it will preserve the original thread layout, formatting, or attachments.

Do not select “Delete all activity history,” delete the visible thread, reset Copilot, or clear application data while recovery is pending.

2. Check whether a personal account is still migrating

Microsoft states that personal-account chats move automatically to the updated Copilot app, but completion time varies with the amount and type of content. Temporary functionality gaps can occur during rollout. That means the symptoms alone do not establish whether this thread is still migrating or is corrupted. ^2^

If this is a personal account:

1. Open a new private/InPrivate browser window.
2. Go to copilot.microsoft.com.
3. Sign in using exactly the same method as before:
   • For a Microsoft account, use that Microsoft account.
   • For a Google or Apple identity, select Continue with Google or Continue with Apple rather than creating or choosing another account.
4. Observe the result:
   • If the browser remains on copilot.microsoft.com, the account has not fully moved. Try opening the thread there and copy its contents immediately.
   • If it redirects to copilot.com, the account has moved or is completing the move.
5. Check the updated app for any migration message or link that provides access to existing chats. ^2^

Because the same single thread fails on Android and desktop while remaining visible, further local reinstalls or cache clearing are unlikely to retrieve that specific conversation. Similar reports exist for long-running threads after the update, but there is no published service incident in the available Microsoft material for this exact error. ^3^

3. Escalate the inaccessible thread

For a personal account, report it from Copilot:

1. Select … in the upper-right corner.
2. Select Send feedback → Report a problem.
3. Include:
   • The conversation title.
   • Approximate creation and last-access dates.
   • That it contains approximately four months of daily messages.
   • The exact Android and desktop errors.
   • When the Copilot update occurred.
   • Screenshots showing the thread in the history list and both loading failures.
   • Whether the private-window migration test stayed on the old site or redirected.

This is the documented escalation route for updated-app content problems. ^2^

For a work or school Microsoft 365 account, ask the Microsoft 365 administrator to open a support request through the Microsoft 365 Admin Center. The administrator can also investigate preservation or export through Microsoft Purview Content Search/eDiscovery: Microsoft stores prompts and responses as Copilot activity history and documents that administrators can search this data with Purview. ^4^

Retention policies can affect availability, so the administrator should perform the search promptly and avoid changing retention settings during the investigation. Copilot messages can remain searchable by eDiscovery until permanently deleted. ^5^

References

1. Manage your Copilot activity history in the privacy dashboard | Microsoft Support
2. Troubleshoot Your Content in the Updated Copilot App | Microsoft Support
3. After Copilot upgrade, I am unable to load my most recent chat with ...
4. Data, Privacy, and Security for Microsoft Copilot
5. Learn about retention for Copilot & AI apps