Microsoft 365 Security Defaults breaks Outlook Password

Fixing Outlook endlessly asking for a password after Security Defaults is enabled

When you enable Security Defaults in Microsoft 365 and for some users, their Outlook asks for a password over and over again, always and forever – even on clean profiles. Here is the fix that worked for me. This worked on Windows 10 computers running the latest versions of the Microsoft Office 365 software.

This is a fast publish – mainly so I can remember the fix.

First Steps

  • Make sure Windows and Office software is up to date
  • Clear all 365 and outlook related items from the Windows Credential Manager

Check Modern Authentication

Ensure Modern Authentication is enabled on the tenant. Source article

Open powershell and connect to exchange online:

Import-Module ExchangeOnlineManagement

Connect-ExchangeOnline -UserPrincipalName [email protected]

Set-OrganizationConfig -OAuth2ClientProfileEnabled $true

Get-OrganizationConfig | Format-Table Name,OAuth* -Auto

Add Registry Keys

Add following registry keys. This tells outlook to pop open the 365 authentication windows instead of the old outlook username and password dialogue box: Source Article

New DWORD Value: AlwaysUseMSOAuthForAutoDiscover

In the Value data box, type 1


New DWORD Value: EnableADAL

In the Value data box, type 1

Adam Mohr
Adam Mohr