Get the correct CalDAV server name for the Calendar server authentication error message. Also find information about an alternate sync method using the Yahoo! Mail header in the Setup Wizard.

You may have an incorrect server name

• Correct the server name: If you received a server authentication error message indicating that the server name you entered for CalDAV is incorrect, you may need to add the correct server name.
• About CalDAV: CalDAV is a calendar syncing protocol used to make calendar data interchangeable with other calendars.

Add the correct CalDAV server name:

• Type the server name below into the CalDAV Server box.
  - Correct server name: https://caldav.calendar.yahoo.com

If you continue to receive an error message:

• Refer to your mobile carrier for further assistance with this issue.
• This issue is with their product, and they will be able to give you the information you need for resolving it.

• Recommendation: We recommend using the Yahoo! Mail header in the Setup Wizard for syncing to Yahoo! Calendar, as the Yahoo! Mail header is more stable.
  - For instructions, see our help article about how to use the Yahoo! Mail header in the Setup Wizard for syncing.