Outlook 2016 and Exchange Online Repeated Credential Prompt

[Himanshu Singh]

• When using Outlook 2016 Professional Plus on Windows 10 (1803) to connect to a synced user's mailbox
  • There is an issue of Repeated Authentication Prompt - It never connects

• While from the same machine I am able to connect to a mailbox for a cloud user fine
• Sign in to Skype for Business for a directly created in cloud user also works fine

• When using Outlook 2016 Professional Plus on Windows 7 to connect to a synced user's mailbox
  • THERE IS NO ISSUE AT ALL THIS WORKS FINE
  • Not sure if windows 7 is able to connect to a mailbox of a cloud user (apparently it should)
  • However Sign in to Skype for Business for a directly created in cloud user doesn't work at all

• When using Outlook 2016 Professional Plus on Windows 10 (14939) to connect to a synced user's mailbox, 
  • There are Prompts here & there but it works tested sending-receiving is WOKING FINE
  • Again connecting mailbox & skype sign in for a directly cloud created account also works fine 

• Remote connectivity analyzer results appear to be identical for Windows 7 & Windows 10

Windows and Outlook versions in use

Microsoft Outlook 2016 MSO (16.0.4639.100) 32 bit

Microsoft Windows 10 Enterprise
Winver Version 1803 (OS BUILD 171134.112)
Msinfo32 Version 10.0.17134 Build 17134

[#2 · Accepted solution]

I was able fix Issue actually there two issues,

1. Oauth was required to be enabled on exchange online at the tenant level (for exchange only) no other application is affected by as the command to do it is an exchange specific commandlet

2. Then there was an additional authentication prompt experienced by the users whose mailbox was migrated to office 365 (EXO) for that there is a registry key

Info about the AllowAdalForNonLyncIndependentOfLync setting in Skype for Business, Lync 2013, and Exchange Online
https://support.microsoft.com/en-in/help/3082803/info-about-the-allowadalfornonlyncindependentoflync...

[#3]

@Himanshu Singh 

I am having the same issue, but nothing has fixed. As, soon as I start Office 365\Outlook on my Windows 10 desktop, I get the following Windows Security prompt as shown on screen.

I installed this on Windows 10 Desktop which is running on Citrix VDI

[#4]

@oryxway 

Did you tried Support and Recovery Assistant from MS to fix the issue. If not try that you may download it from the below link...

https://diagnostics.outlook.com/#/

Thanks

Robin Nishad