Outlook prompts for password when Modern Authentication is enabled

Symptoms

Consider the following scenarios.

Scenario 1:
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.

Scenario 2:
You migrate your mailbox to Office 365 from an Exchange server that Outlook connects to by using RPC.

In these scenarios, you may be prompted for credentials, and Outlook doesn't use Modern Authentication to connect to Office 365. After you enter your credentials, they are transmitted to Office 365 instead of to a token.

Cause

Outlook limits its choices of authentication schemes to schemes that are supported by RPC. This does not include Modern Authentication.

Resolution

Important 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 in case problems occur.

Create the following registry key in order to force Outlook to use the newer authentication method for web services, such as EWS and Autodiscover.
  1. Exit Outlook.
  2. Start Registry Editor. To do this, use one of the following procedures, as appropriate for your version of Windows:
    • Windows 10, Windows 8.1 and Windows 8: Press Windows Key + R to open a Run dialog box. Type regedit.exe, and then press Enter.
    • Windows 7: Click Start, type regedit.exe in the search box, and then press Enter.

  3. In Registry Editor, locate and then click the following registry subkey: 

    HKEY_CURRENT_USER\Software\Microsoft\Exchange
  4. On the Edit menu, point to New, and then click DWORD Value.
  5. Type AlwaysUseMSOAuthForAutoDiscover, and then press Enter.
  6. Right-click AlwaysUseMSOAuthForAutoDiscover, and then click Modify.
  7. In the Value data box, type 1, and then click OK.
  8. Exit Registry Editor.

More Information

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.

3114349 December 8, 2015, update for Outlook 2013 (KB3114349)

3114333 December 8, 2015, update for Office 2013 (KB3114333)

Note Office 2016 does not require an update for this registry key to work.
Właściwości

Identyfikator artykułu: 3126599 — ostatni przegląd: 02.06.2016 — zmiana: 1

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