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Microsoft Entra Blog
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Azure AD Mailbag: Discovering and blocking legacy authentication

Sue Bohn's avatar
Sue Bohn
Icon for Microsoft rankMicrosoft
Mar 15, 2019
Hey there,   I am Andres Canello from the Azure AD Get-to-Production team. I'm a long time Exchange guy now working on Identity. I am very passionate about helping customers prevent password-base...
Updated Jul 24, 2020
Version 14.0
Customer and Partner
Thomas Foster's avatar
Thomas Foster
Copper Contributor
Jul 03, 2019

I'm having similar behavior to the people above me. We have been using Modern Auth with a Conditional Access Policy that integrates Duo 2FA. When enabling the preview policy to disable legacy auth, about 5% of users are unable to authenticate through any Office365 bundled applications (Teams works fine, Web works fine). I did troubleshooting with one user and even with a freshly installed Office 365 Pro Plus (used the cleanup tool to uninstall and then restart and reinstall) it still fails to authenticate.

 

Basic InfoDevice InfoConditional Access