How to Fix Copilot Asking to Sign In Repeatedly in Office Apps

When you use Copilot in Word, Excel, or PowerPoint, the app may prompt you to sign in again every few minutes. This happens even though your Microsoft 365 account is already connected. The repeated sign-in loop stops your work and blocks access to Copilot features such as draft generation, summary, and chat. This article explains why Copilot loses authentication in Office apps and provides step-by-step fixes to stop the sign-in loop permanently.

Why Copilot Keeps Asking You to Sign In in Office Apps

The root cause is a mismatch between the cached authentication token stored on your device and the token that the Microsoft identity platform expects. Microsoft 365 apps use the Microsoft Authentication Library to obtain tokens that last several hours. When the cached token becomes corrupted, expires prematurely, or conflicts with a second token from a different account, the Office app cannot validate your identity. Copilot then displays the sign-in prompt again.

Several triggers can cause this token mismatch:

Corrupted Windows Credential Manager entries

Office apps store sign-in data as Windows credentials. If the entry for MicrosoftOffice16_Data becomes damaged, the app cannot reuse the stored token and forces a new sign-in.

Multiple Microsoft 365 accounts signed in simultaneously

When you add a work account and a personal account in the same Office app, the token cache may confuse which account owns the Copilot license. The app then asks the wrong account to sign in again.

Outdated Office version

Older builds of Microsoft 365 Apps for enterprise do not handle token refresh correctly. An update from Microsoft fixes the renewal logic.

Steps to Stop the Repeated Sign-In Prompt for Copilot

Perform these steps in the order listed. Test Copilot after each step to see if the sign-in loop is resolved before moving to the next method.

Method 1: Clear Windows Credentials for Office

1. Open Credential Manager
   Press the Windows key, type Credential Manager, and press Enter.
2. Switch to Windows Credentials
   Click Windows Credentials in the top section of the window.
3. Locate MicrosoftOffice16_Data entries
   Scroll down to the Generic Credentials section. Look for entries starting with MicrosoftOffice16_Data followed by your Microsoft 365 account email address.
4. Remove each stale entry
   Click the arrow to expand the entry, then click Remove. Confirm the deletion. Repeat for every MicrosoftOffice16_Data entry that belongs to your work or school account.
5. Restart the Office app
   Close Word or Excel completely. Reopen the app and sign in again when prompted. Copilot should now retain the sign-in state.

Method 2: Sign Out and Sign Back In from the Office App

1. Open any Office app
   Launch Word, Excel, or PowerPoint.
2. Go to File > Account
   Click File in the top-left corner, then click Account in the left navigation pane.
3. Sign out of your account
   Under User Information, click Sign Out. Wait for the app to disconnect.
4. Restart the app and sign in
   Close and reopen the app. Click Sign In and enter your Microsoft 365 credentials. This action issues a fresh token that Copilot can use without interruption.

Method 3: Repair Office Installation

1. Open Windows Settings
   Press Windows key + I.
2. Go to Apps > Installed apps
   Click Apps on the left, then click Installed apps.
3. Find Microsoft 365
   Scroll to Microsoft 365 Apps for enterprise or Microsoft 365. Click the three-dot menu next to it and select Modify.
4. Choose Quick Repair
   In the Microsoft Office setup window, select Quick Repair and click Repair. If the problem persists, run Online Repair which requires an internet connection and takes longer.
5. Restart and test
   After the repair completes, restart your computer. Open an Office app and use Copilot to verify the sign-in loop is gone.

If Copilot Still Has Issues After the Main Fix

Copilot asks to sign in only in one Office app but not in others

This indicates a corrupt app-specific cache. Close the affected app, press Windows key + R, type %appdata%\Microsoft\Office\16.0, and press Enter. Delete the folder named Licensing. Restart the app and sign in again.

Copilot sign-in prompt appears every time the computer wakes from sleep

The token refresh fails after the network reconnects. Open the affected app, go to File > Account > Connected Services, and remove any duplicate accounts. Keep only one work or school account. Then restart the app.

Copilot shows an error saying your account needs reauthentication

Your organization may have configured conditional access policies that require reauthentication every hour. Contact your Microsoft 365 administrator. They can check the sign-in logs in the Azure portal under Azure Active Directory > Sign-ins to see if the session is being revoked.

Manual Token Reset vs Credential Manager Clear: Key Differences

Item	Manual Token Reset (Sign Out / Sign In)	Credential Manager Clear
Scope	Clears in-memory token for the current app only	Removes all stored tokens for Office apps on the device
Effort	Low, requires two clicks inside the app	Medium, requires opening Credential Manager and deleting entries
Persistence of fix	May last only until the next Office update or network change	Usually permanent until a new token corruption occurs
Effect on other Microsoft services	No effect on Outlook, Teams, or OneDrive	May require re-sign-in for Outlook and OneDrive as well

After you clear credentials or reset the token, Copilot in Word, Excel, and PowerPoint will remember your sign-in state across sessions. To prevent the issue from recurring, keep your Microsoft 365 Apps for enterprise updated to the latest Semi-Annual Enterprise Channel build. You can check for updates by going to File > Account > Update Options > Update Now. If you manage multiple accounts in Office, remove the secondary account from File > Account > Connected Services to avoid token conflicts.