Consider the following scenarios.<\/p>\n\n\n\n
Scenario 1<\/strong>:<\/p>\n\n\n\n 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.<\/p>\n\n\n\n Scenario 2<\/strong>:<\/p>\n\n\n\n You migrate your mailbox to Office 365 from an Exchange server that Outlook connects to by using RPC.<\/p>\n\n\n\n In these scenarios, you’re prompted for credentials, and Outlook doesn’t use Modern Authentication to connect to Office 365. After you enter your credentials, they’re transmitted to Office 365 instead of to a token.<\/p>\n\n\n\n Outlook limits its choices of authentication schemes to schemes that are supported by RPC. But the authentication schemes don’t include Modern Authentication.<\/p>\n\n\n\n Important<\/p>\n\n\n\n Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration<\/a> in case problems occur.<\/p>\n\n\n\n Create the following registry key to force Outlook to use a newer authentication method for web services, such as EWS and Autodiscover. We recommend that users force Outlook to use Modern Authentication.<\/p>\n\n\n\n If you’re running Office 2013, make sure that both Outlook and MSO are updated to the December 12, 2015 updates, or a later update release, before you use this registry key.<\/p>\n\n\n\n 3114349<\/a> December 8, 2015, update for Outlook 2013 (KB3114349)<\/p>\n\n\n\n 3114333<\/a>\u00a0December 8, 2015, update for Office 2013 (KB3114333)<\/p>\n\n\n\nCause<\/h2>\n\n\n\n
Resolution<\/h2>\n\n\n\n
HKEY_CURRENT_USER\\Software\\Microsoft\\Exchange<\/strong><\/code><\/li>More information<\/h2>\n\n\n\n