M365 Account issue Office 2013

[Matt_Taylor2]

I am experiencing issues with adding M365 accounts to workstations with Office 2013. Some workstations within our environment have Office 2013 and allow M365 accounts to be added but a few don't. 

The issue is that the Outlook 2013 is still using legacy authentication even though the correct steps have been followed to make sure that Modern Authentication is enabled. 

I have added the recommended registry keys from (https://docs.microsoft.com/en-us/microsoft-365/admin/security-and-compliance/enable-modern-authentic...) and have also made sure that the users workstation has the necessary windows updates from (https://docs.microsoft.com/en-us/officeupdates/outlook-updates-msi).

The user can access the M365 account using OWA so there is not an issue with the account. 

It should be noted that clients also connect to an internally hosted Exchange 2016 service without any problem. 

If anyone has any suggestions of how to stop Office 2013 from using Legacy Authentication, it would be very appreciated!

[#2]

Modern auth needs to be enabled both server- and client-side, and older tenants dotn have the server-side bits enabled by default, so check for that. Also, make sure to clear any stored credentials from cred manager.

[#3]

@Vasil Michev Thanks for your reply. Its enabled on the server as other clients can access their M365 accounts using Office 2013. Its only affecting a few users. 

Cleared credentials from Cred manager but hasn't made a difference.