The Copilot pane in Microsoft 365 apps like Word, Excel, and Teams repeatedly asks you to sign in again, even when you are already authenticated. This loop prevents you from using Copilot features such as drafting documents or summarizing emails. The primary cause is a corrupted or expired authentication token that Microsoft 365 cannot refresh silently. This article explains why the sign-in prompt recurs and provides step-by-step fixes to clear the token cache and restore persistent access.
Key Takeaways: Stop the Copilot Sign-In Loop
- Windows Credential Manager > Windows Credentials > MicrosoftOffice16_Data:ADAL: Deleting these entries forces a fresh token request and resolves stale authentication.
- Microsoft 365 admin center > Health > Service Health: Check for active Copilot service incidents that cause repeated sign-in prompts.
- Outlook > File > Account Settings > Account Settings > Repair: Running the repair tool resets the Outlook profile and associated Copilot token cache.
Why Copilot Keeps Asking You to Sign In Again
When you sign into Microsoft 365, the system issues an access token and a refresh token. The access token expires after a set period, typically one hour. The refresh token silently requests a new access token without interrupting your work. If the refresh token is corrupted, expired beyond its validity window, or blocked by a Conditional Access policy, the client cannot obtain a fresh token. The app then falls back to showing the sign-in dialog because it cannot authenticate silently.
Another common cause is a mismatch between the stored token and the current tenant or user account. This happens after a tenant migration, a password reset, or when multiple work accounts are cached on the same device. The Copilot service rejects the stale token, and the app interprets the rejection as a sign-in requirement.
Conditional Access Policies and Token Refresh
If your organization enforces Conditional Access policies that require device compliance or multi-factor authentication at each session, the refresh token may be invalidated more frequently. Microsoft 365 Copilot uses the same authentication framework as the host app. Any policy that forces re-authentication for the host app also triggers the sign-in prompt for Copilot.
Steps to Clear the Stored Token and Stop the Sign-In Loop
- Close all Microsoft 365 apps
Exit Word, Excel, Outlook, Teams, and any other Microsoft 365 applications. Make sure no Office processes remain running in the background. Open Task Manager and end any task named WINWORD.EXE, EXCEL.EXE, OUTLOOK.EXE, or Teams.exe. - Open Windows Credential Manager
Press the Windows key, type Credential Manager, and select the app from the search results. Click Windows Credentials to view stored web and app credentials. - Delete all MicrosoftOffice16_Data:ADAL entries
Scroll through the Generic Credentials section. Look for any entry that starts with MicrosoftOffice16_Data:ADAL:. Each entry represents a cached token for a Microsoft 365 account. Click the arrow to expand the entry, then click Remove. Confirm the deletion. Repeat this for every entry that contains ADAL in the name. - Delete MicrosoftOffice16_Data:MSOL entries
Similarly, find and remove any entry that starts with MicrosoftOffice16_Data:MSOL:. These are legacy tokens that can interfere with modern authentication. - Reopen a Microsoft 365 app and sign in
Open Word or Outlook. You will see the sign-in prompt. Enter your work or school account credentials and complete any multi-factor authentication required. Copilot should now stay signed in without repeating the prompt.
Alternative Method: Reset the Microsoft 365 Activation
If deleting credential entries does not work, reset the activation state of Office. Open a Command Prompt as administrator. Navigate to the Office installation folder, typically C:\Program Files\Microsoft Office\Office16. Run the command cscript ospp.vbs /dstatus to view the current license status. Then run cscript ospp.vbs /unpkey:XXXXX where XXXXX is the last five characters of the product key shown in the status output. Finally, open any Office app and sign in again to reactivate. This clears all cached tokens and forces a fresh authentication flow.
If Copilot Still Shows the Sign-In Prompt After the Main Fix
Copilot sign-in prompt appears only in Outlook
Outlook caches its own authentication profile separately from other Office apps. Close Outlook. Open Control Panel and go to Mail (Microsoft Outlook). Click Show Profiles, select your current profile, and click Remove. Create a new profile by clicking Add, entering a profile name, and signing in with your Microsoft 365 credentials. Open Outlook with the new profile. The Copilot pane should no longer request a sign-in.
Copilot sign-in prompt appears every time you switch networks
Some Conditional Access policies tie the refresh token to a specific IP range or network location. When you move from the office network to a public Wi-Fi or VPN, the token is no longer valid. Contact your IT admin and ask them to review the Conditional Access policies for the Office 365 app. They can configure the policy to use Persistent Browser Session or adjust the sign-in frequency to reduce token invalidation.
Copilot sign-in prompt appears after a password change
When you reset your Microsoft 365 password, all existing refresh tokens are revoked. You must sign in again on every device and app. The token deletion steps in the main fix are the fastest way to clear the old credentials. After the password change, wait 15 minutes before attempting to sign in to allow the new token to propagate across Microsoft servers.
Manual Token Clear vs Automatic Repair: Which Method Works Faster?
| Item | Manual Credential Deletion | Office Repair Tool |
|---|---|---|
| Time required | 5 to 10 minutes | 15 to 30 minutes |
| Scope | Removes only Microsoft 365 tokens | Repairs all Office files and settings |
| Network requirement | No internet needed for deletion step | Requires download of repair files |
| Risk of data loss | None | Low, but may reset custom settings |
| Best for | Single user with token corruption | Multiple Office issues beyond sign-in |
For most users, the manual credential deletion method is faster and more targeted. Only use the Office Repair Tool if you also experience crashes, missing features, or file corruption alongside the sign-in loop.
You can now stop the recurring Copilot sign-in prompt by deleting the ADAL and MSOL entries in Windows Credential Manager. If the issue persists in Outlook, create a new mail profile to reset its token cache. For recurring prompts after network changes, ask your IT admin to review Conditional Access policies and adjust the sign-in frequency setting for the Office 365 app suite.