Office 2016

Office 365/Outlook 2016 with MFA and the dreaded Password prompt of doom

Posted by robd on October 12, 2018
Exchange Online / No Comments

We recently started implementing Multiple Factor Authentication with office 365 and today I ran into a weird issue while working from home.

Laptop – Windows 10 1703

Outlook 2016 – 16.0.7726.1049

While opening Outlook 2016 I was prompted for my 365 credentials (over and over again) without any MFA prompt.

Would not not go away and would not connect.

So I checked

OWA – https://outlook.office365.com/owa – worked no problem and was prompted with MFA.

Teams – local install, worked no bother with MFA.

So I went to Azure Active Directory and could see loads of failed attempts:

Specifically: User did not pass MFA challenge (non Interactive)

So my guess was Outlook wasnt prompting me for MFA for what ever reason. I tried a new Outlook profile which wouldnt connect and the following registry entried to try and force basic connections from Outlook:

HKCU\SOFTWARE\Microsoft\Office\16.0\Common\Identity\EnableADAL

dword value 0

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity

DisableADALatopWAMOverride

dword value 1

None of this worked so I went all out and did the following which fixed the issue:

  1. Sign out of Office 365
    1. Open Word
    2. In the upper-right corner of the Office 2016 app, click your name, and then click Switch Account.
    3. On the Accounts screen, click Sign out.
    4. Locate the account that you want to remove, and then click Sign out.
  2. Remove the cached credentials in Credentials Manager.
    1. To do this, follow these steps: Open Control Panel, and then click Credentials Manager.
    2. Under Windows Credentials, remove all the accounts under Generic Credentials
  3. Clear cached credentials on the computer from the registry.
    1. Click Start, click Run, type regedit, and then click OK.
    2. In Registry Editor, locate and backup then delete the following registry subkey:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities

4. Launch Word and sign into Office 365 (it logged in without issue)

5. Launch Outlook and I was prompted for my MFA credentials and which I authenticated via my phone and I was in.

 

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