Outlook limits its choices of authentication schemes to schemes that are supported by RPC. But the authentication schemes don't include Modern Authentication. This may result in outlook asking for password for a previous older version of Outlook (2013 or 2016)  and the current password does not work. Here are the steps to solve:


  1. Exit Outlook.

  2. Uninstall Old version of Outlook

  3. Reboot

  4. Start RegEdit

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

  6. HKEY_CURRENT_USER\Software\Microsoft\Exchange

  7. On the Edit menu, point to New, and then click DWORD Value.

  8. Type AlwaysUseMSOAuthForAutoDiscover, and then press Enter.

  9. Right-click AlwaysUseMSOAuthForAutoDiscover, and then click Modify.

  10. In the Value data box, type 1, and then click OK.

  11. Exit Registry Editor.

  12. Install new version of Outlook and open