After updating a Dynamics 365 (online) organziation to version 9.0 the Dynamics 365 for Outlook client is unable to connect.
A Dynamics 365 (online) organziation on version 9.0 requires TLS 1.2.
Microsoft has released Dynamics 365 for Microsoft Outlook version 126.96.36.199 update. This update includes support for Transport Layer Security (TLS) 1.2.
The update can be found below: