Outlook Prompting for SharePoint Login Credentials

Symptoms: While using Outlook, users receive prompts asking for their username and password for a SharePoint site, and Outlook displays an error message during Send/Receive stating “Outlook cannot connect to the SharePoint List [List Name]. The server may not be reachable from your location.

Cause: The user has used the “Link to Outlook” feature to make items in a SharePoint List, Calendar, or Document Library available directly from Outlook. The error states that Outlook is experiencing difficulties with the sync process to that SharePoint list.  This is a particularly annoying error because Outlook is set to sync every few minutes, so the error message is repeated often.

 Send Recieve Outlook Error

The three most common causes for the sync problem are:

The three most common causes for the sync problem are:

  • A temporary SharePoint server  connection problem
  • A  deleted or renamed list or library (the URL has changed)
  • (Most commonly) a connection established in a prior version of Outlook did not upgrade correctly when the user switched to a new Office version


 To troubleshoot, first check to see if it was a temporary server problem my doing a Send/ Receive All in Outlook. If the error occurs (choose the option to Show Progress of the Send/Receive), it’s not a server error.
SharePoint Lists folder in OutlookNext, make sure the location still exists in SharePoint. In Outlook, click the folder icon on the bottom left of the inbox to show all folders in the list on the left side of the screen.

Expand the SharePoint Lists folder and right-click the list mentioned in the error. Choose Open in a Web Browser to see if the destination URL still exists. If the URL is broken, delete the connection as explained below. If the URL is good but the sync is still encountering the error, delete the connection and then reestablish it as explained below.  

To Delete the Connection: From the SharePoint Lists in Outlook, right-click the connection causing the error and choose Delete. You’ll get a dire message about deleting the contents, but don’t worry. You’re only deleting the connection and the copies of the docs in Outlook. The original documents in SharePoint will not be deleted.

To Reestablish the Connection: If the connection is still needed by the user, navigate to the list in SharePoint, and from the ribbon, choose the List tab, and then the option to Connect to Outlook (hover over the icons if needed…this is in the middle of the ribbon near the Excel icon). You’ll get two prompts when you Connect to Outlook, one from SharePoint and one from Outlook. Confirm both. The connection is reestablished and a Send/Receive All action should process without error.


About Joy Lavigne (Adkins)

SharePoint and O365 Business Analyst for a mid-sized organization. Recovering SharePoint on-prem Administrator. Frequent speaker at SharePoint Saturday events. Teller of terribly corny jokes. View all posts by Joy Lavigne (Adkins)

2 responses to “Outlook Prompting for SharePoint Login Credentials

  • Stuart

    Thanks! This has been annoying me for some time! Your post pointed me in the direction of an old SharePoint Calendar. As soon as I removed it, no more Windows Security popups in Outlook! 🙂

  • Colin

    This has been plaguing me for weeks and weeks and your instructions also pointed me to an old calendar. Deleted it, and problems solved.

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