We recommend that users force Outlook to use Modern Authentication. Before you modify it, back up the registry for restoration in case problems occur.Ĭreate the following registry key to force Outlook to use a newer authentication method for web services, such as EWS and Autodiscover. Serious problems might occur if you modify the registry incorrectly. Resolutionįollow the steps in this section carefully. But the authentication schemes don't include Modern Authentication.
Outlook limits its choices of authentication schemes to schemes that are supported by RPC. After you enter your credentials, they're transmitted to Office 365 instead of to a token. In these scenarios, you're prompted for credentials, and Outlook doesn't use Modern Authentication to connect to Office 365. You migrate your mailbox to Office 365 from an Exchange server that Outlook connects to by using RPC.
Microsoft Outlook connects to your primary mailbox in an on-premises Exchange server by using RPC, and it also connects to another mailbox that's located in Office 365. Outlook prompts for password and doesn't use Modern Authentication to connect to Office 365
