However, some servers consider the broadcast to be an invalid client request. Most server software responds to this broadcast by supporting modern authentication. Even if the Internet calendar file that you are trying to open does not require authentication, Outlook broadcasts its ability to do modern authentication on the server that contains the calendar. Additionally, you don't receive any error message.īy default, Outlook 2016, Outlook 2019 and Outlook for Office 365 use a new modern authentication stack.
After a progress window opens briefly, you are returned to the calendar module without a new calendar added. When you use this method for some Internet servers, the calendar is not added successfully. Provide the path of your Internet calendar file. In the Manage Calendars group on the toolbar, click Open Calendar. You try to add an Internet calendar in Microsoft Outlook 2016, Outlook 2019 or Outlook for Office 365 by following these steps: Can't add an Internet calendar in Outlook 2016, Outlook 2019 and Outlook for Office 365
