Based on the supported guidance, the most likely cause is that the old chats are still tied to the sign-in method/account context used before the update, or the migration is still completing.
Supported steps:
- Verify the exact sign-in method used before the update If the chats were originally used with Google sign-in, use the same sign-in option again. For a Gmail-based account, that means selecting Continue with Google rather than signing in through the Microsoft account flow. Microsoft states that the same personal email or sign-in option previously used should be used.
- Check whether the correct account is active Personal accounts and work or school accounts remain separate. Use the account switcher and confirm the correct personal account is selected.
- Try a private browsing session for each personal account If multiple personal accounts are involved, open a new private browsing session, go to Copilot, and sign in with the personal account to check. If the session redirects to the updated experience, that account has moved or is completing the move. If it remains on the older Copilot site, that account has not moved yet and can still be used there until it moves later.
- Restart and recheck across devices Close and reopen the Copilot app on each device, or refresh the web page. Microsoft states that data movement and sync across devices can take time.
- Use any in-app link to previous chats if shown If content is still being moved, the app may show a link to access existing chats temporarily.
- Report the problem from the Copilot app
If the chats are still missing, use:
- … in the upper-right corner
- Send feedback
- Report a problem
- when the problem started
- device and operating system
- a screenshot of the issue
What is supported about the account-linking question:
- If Copilot was used with more than one linked personal account, such as a Google email and a personal Microsoft email, Copilot history, preferences, and eligible content are brought together into the updated app through the Microsoft account.
- No action is required for that linking behavior.
- Personal and work/school accounts remain separate.
What is not supported by the available guidance:
- There is no supported confirmation method here for whether migration completed successfully on Microsoft’s servers.
- There is no supported way here to check whether missing chats still exist on Microsoft’s servers.
- There is no supported guidance here that old chat IDs from direct conversation URLs can be used to recover chats.
- There is no supported self-service process here to restore or manually re-associate historical conversations.
One important limitation is also documented: some content may not carry forward because certain features were retired. However, normal chats, images, and most other eligible Copilot content are expected to move.
- Troubleshoot Your Content in the Updated Copilot App | Microsoft Support
- Troubleshoot Your Content in the Updated Copilot App | Microsoft Support
- Troubleshoot Your Content in the Updated Copilot App | Microsoft Support
- Troubleshoot Your Content in the Updated Copilot App | Microsoft Support
- Copilot App Updates for Personal, Work, and School Accounts | Microsoft Support