Outlook Keeps Asking for Password After Tenant Migration: Fix

After a tenant-to-tenant migration in Microsoft 365, Outlook may repeatedly prompt you for your password even though you have already entered the correct credentials. This happens because Outlook caches the old authentication tokens and server endpoints from the previous tenant. The cached data conflicts with the new tenant configuration, causing authentication loops. This article explains why the password prompt persists and provides step-by-step fixes to clear stale credentials and restore normal access.

Why Outlook Keeps Asking for Password After a Tenant Migration

When a Microsoft 365 tenant migration occurs, the underlying user identity moves from one Azure Active Directory tenant to another. Outlook stores authentication tokens, Autodiscover endpoints, and connection settings locally. These cached values still point to the old tenant’s domain and authentication servers.

Even after you update your password on the new tenant, Outlook continues to present the old token to the server. The new tenant rejects this token because the user object no longer exists in the old tenant or the token’s issuer is invalid. Outlook then shows the password prompt again.

The issue is not caused by a wrong password. It is a credential mismatch between what Outlook holds locally and what the new tenant expects. Clearing the cached credentials and forcing a fresh authentication cycle resolves the problem.

Steps to Clear Cached Credentials and Stop Password Prompts

Perform the following steps in order. Test Outlook after each step to see if the prompt stops. Move to the next step only if the prompt persists.

Step 1: Remove Stored Credentials from Windows Credential Manager

1. Open Credential Manager
   Press the Windows key and type Credential Manager. Click the result to open the Control Panel app.
2. Switch to Windows Credentials
   In Credential Manager, click Windows Credentials. This section stores Outlook-related credentials.
3. Locate Outlook credentials
   Scroll down to the Generic Credentials section. Look for entries that start with MicrosoftOffice15_Data, MicrosoftOffice16_Data, or Outlook followed by a server address.
4. Remove each entry
   Click the arrow next to each entry to expand it, then click Remove. Confirm the deletion when prompted. Remove all entries related to Outlook and the old tenant domain.
5. Restart Outlook
   Close Outlook completely and reopen it. Enter your new tenant password when prompted.

Step 2: Clear Outlook Autodiscover Cache

1. Close Outlook
   Ensure Outlook is not running. Check Task Manager if necessary.
2. Delete the Autodiscover XML cache
   Press Windows + R, type %localappdata%\Microsoft\Outlook, and press Enter. In the folder that opens, delete all files that start with Autodiscover or Outlook and end with .xml. These files contain cached Autodiscover responses from the old tenant.
3. Delete the OST file (optional but recommended)
   In the same folder, locate the .ost file for your mailbox. Its name matches your email address. Delete the .ost file. Outlook will recreate it when it next starts.
4. Restart Outlook
   Open Outlook. It will perform a fresh Autodiscover lookup against the new tenant and prompt for your password.

Step 3: Repair the Outlook Account

1. Open Account Settings
   In Outlook, go to File > Account Settings > Account Settings.
2. Select your account and click Change
   Highlight the email account that is prompting for a password. Click Change.
3. Run the Repair tool
   In the window that opens, click Repair. Follow the on-screen instructions. The repair process reconfigures the account settings and forces re-authentication.
4. Restart Outlook
   After the repair completes, restart Outlook and enter your new password.

Step 4: Create a New Outlook Profile

1. Open Mail in Control Panel
   Press Windows + R, type control mlcfg32.cpl, and press Enter. This opens the Mail setup dialog.
2. Show Profiles
   Click Show Profiles. Select your current profile and click Remove. Confirm the deletion.
3. Create a new profile
   Click Add. Enter a name for the new profile, such as Work. Follow the prompts to add your email account. Outlook will perform a fresh Autodiscover and connect to the new tenant.
4. Set the new profile as default
   Under When starting Microsoft Outlook, use this profile, select your new profile from the drop-down list. Click OK.
5. Restart Outlook
   Open Outlook and verify that the password prompt no longer appears.

If Outlook Still Has Issues After the Main Fix

Outlook Prompts for Password After Every Restart

If the password prompt returns after each restart, a corrupted registry entry for Modern Authentication may be blocking token refresh. Press Windows + R, type regedit, and press Enter. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Exchange\AlwaysUseMSOAuthForAutoDiscover. Set the value to 1. If the key does not exist, create a DWORD (32-bit) with that name and set it to 1. Restart Outlook.

Outlook Shows Disconnected or Needs Password in Status Bar

This often indicates that the new tenant requires Modern Authentication but Outlook is configured for Basic Authentication. In Outlook, go to File > Account Settings > Account Settings. Select your account and click Change. Under Logon Information, ensure Require logon using Exchange Web Services is unchecked. Then close Outlook, delete the MicrosoftOffice16_Data entries from Credential Manager again, and restart Outlook.

Outlook Cannot Connect to the New Tenant at All

If Outlook cannot connect after creating a new profile, the Autodiscover DNS record for the new tenant may not be set up correctly. Ask your tenant administrator to verify that the Autodiscover CNAME record points to autodiscover.outlook.com and that the user’s primary SMTP address matches the new domain. You can test Autodiscover by visiting https://testconnectivity.microsoft.com and running the Outlook Autodiscover test.

Password Prompt Causes After Tenant Migration: Common Scenarios

Item	Old Tenant (Before Migration)	New Tenant (After Migration)
Authentication token issuer	login.microsoftonline.com/old-tenant-id	login.microsoftonline.com/new-tenant-id
Autodiscover endpoint	autodiscover.olddomain.com	autodiscover.outlook.com
User object location	Azure AD old tenant	Azure AD new tenant
Outlook profile server name	olddomain.com	newdomain.com
Credential Manager entries	MicrosoftOffice15_Data:olddomain.com	MicrosoftOffice15_Data:newdomain.com

The table above shows why Outlook fails to authenticate after migration. Every component must point to the new tenant. The fixes in this article replace the old entries with the new tenant’s values.

You can now stop repeated password prompts by clearing Windows Credential Manager entries, deleting the Autodiscover cache, and repairing or recreating your Outlook profile. If the issue returns, check the Modern Authentication registry key or verify Autodiscover DNS settings with your tenant administrator. As an advanced step, run the Outlook Auto Account Setup diagnostic from the Microsoft Support and Recovery Assistant to identify lingering old tenant references.