Outlook "Cannot Connect to Server" & Microsoft 365 Modern Auth Token Loop
Fix Outlook repeatedly asking for password, "Need Password" prompt loops, and modern authentication connection disconnects.
⚡ Direct Answer & Quick Diagnostic Summary (AEO)
To resolve Microsoft 365 Outlook connection disconnects, "Need Password" loops, and modern authentication credential prompts on Windows 10/11, close Outlook and open Windows Control Panel → Credential Manager → Windows Credentials. Under Generic Credentials, delete all cached tokens beginning with "MicrosoftOffice16", "MS.Outlook", and "ADAL". Open the Windows Run dialog (Win+R), navigate to "%localappdata%\Microsoft\IdentityCache" and "%localappdata%\Microsoft\OneAuth", and delete all cached identity folders inside. In Windows Settings → Accounts → Access Work or School, disconnect the company account and reconnect to re-authenticate via Microsoft Authenticator MFA. In your domain DNS control panel, verify that a CNAME record exists for "autodiscover.yourdomain.com" pointing to "autodiscover.outlook.com". If modern auth fails, run "dsregcmd /leave" in an elevated command prompt to reset device Azure AD registration tokens, then recreate the Outlook profile via Mail Control Panel.
Primary Root Causes
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Step-by-Step Diagnostic Checklist
Step 1: Clear Stale Credentials from Windows Credential Manager
Close Outlook. Open Windows Control Panel → Credential Manager → Windows Credentials. Under Generic Credentials, delete all entries starting with "MicrosoftOffice", "MS.Outlook", and "ADAL".
Step 2: Purge Corrupted IdentityCache AppData Folder
Press Win+R, type "%localappdata%\Microsoft\IdentityCache" and press Enter. Delete all folders inside. Also delete "%localappdata%\Microsoft\OneAuth".
Step 3: Verify Domain Autodiscover CNAME DNS Record
Verify your company domain has an active CNAME record for "autodiscover.yourdomain.com" pointing to "autodiscover.outlook.com". Missing CNAME causes Outlook to fall back to root domain XML lookups.
Step 4: Disconnect and Reconnect Work or School Account
Go to Windows Settings → Accounts → Access work or school. If your Microsoft 365 email is listed, click Disconnect, restart PC, and click Connect to re-authenticate with modern MFA.
Step 5: Create Fresh Outlook Profile via Mail Control Panel
Open Control Panel → Mail (Microsoft Outlook) → Show Profiles. Click "Add", name the new profile, enter your 365 email credentials, and set as default profile.
Frequently Asked Questions
Why does Outlook keep asking for password even though credentials are correct?
This is caused by stale OAuth modern authentication tokens in Windows Credential Manager. Clearing the Generic Credentials and IdentityCache folder forces Outlook to generate a fresh authentication token.
How do I test if Microsoft 365 Autodiscover is working properly?
Hold Ctrl and right-click the Outlook icon in the Windows system tray. Select "Test E-mail AutoConfiguration", uncheck Guessmart, enter your email and password, and click Test.
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