Classic Outlook to New Outlook: SharePoint Calendar Sync – Replace classic connected calendars

You need to sync a SharePoint calendar with the new Outlook for Windows, but the classic method of connecting a SharePoint calendar as an internet calendar no longer works. Microsoft redesigned the sync engine in the new Outlook, replacing the old calendar connection feature with a direct SharePoint site integration. This article explains how to replace classic connected calendars by adding a SharePoint calendar directly from the site, ensuring your team events remain visible in your new Outlook calendar view.

Why Classic SharePoint Calendar Connections Stop Working in New Outlook

The classic Outlook for Windows allowed you to add a SharePoint calendar by copying a calendar URL from the SharePoint site and pasting it into the “From Internet” option under Open Calendar. This created an internet calendar subscription that synced read-only events using the iCalendar format. The new Outlook for Windows, which is built on the same platform as Outlook on the web, does not support internet calendar subscriptions from SharePoint. Instead, it uses a direct connection to the SharePoint site through the Microsoft 365 Graph API. When you attempt to use the old method in new Outlook, the “From Internet” option is either missing or produces an error because the underlying sync protocol changed. To replace classic connected calendars, you must use the SharePoint site itself to initiate the connection.

Steps to Sync a SharePoint Calendar with New Outlook

Follow these steps to add a SharePoint calendar to the new Outlook for Windows. You need a supported Microsoft 365 license that includes SharePoint Online. The new Outlook must be installed and set as the default mail client.

1. Open the SharePoint site in your browser
   Go to the SharePoint site that contains the calendar you want to sync. Sign in with the same Microsoft 365 account you use in new Outlook.
2. Navigate to the calendar list
   On the SharePoint site, select “Lists” in the left navigation pane, then click the calendar list name. If the calendar is not visible, click “Site contents” and locate the calendar list there.
3. Click “Add to Outlook”
   On the command bar at the top of the calendar list, click “Add to Outlook”. If you do not see this button, click the ellipsis (three dots) on the command bar and select “Add to Outlook” from the dropdown menu.
4. Confirm the connection prompt
   A dialog box appears asking whether you want to allow this website to open a link in Outlook. Click “Allow” to proceed. The SharePoint calendar opens in new Outlook automatically.
5. Verify the calendar in new Outlook
   In new Outlook, go to the Calendar module. Look under the “Shared calendars” group in the left navigation pane. The SharePoint calendar appears with the same name as the list on the SharePoint site. Events from the SharePoint calendar now appear alongside your personal calendar.

The sync is one-way from SharePoint to Outlook. Changes made to events in Outlook are not written back to the SharePoint list. To edit an event, open the SharePoint site directly and modify the item in the list.

If the SharePoint Calendar Does Not Appear After Adding It

“Add to Outlook” button is missing from SharePoint

The “Add to Outlook” button may not appear if the SharePoint site is not configured to allow calendar connections. The site owner must enable the “Allow calendar connections” setting in the SharePoint list settings. To check this, go to the calendar list in SharePoint, click the gear icon (Settings) and select “List settings”. Under “Communications”, ensure “Allow calendar connections” is set to “Yes”. If it is set to “No”, the button is hidden and you need to ask the site owner to change it.

Outlook prompts for credentials repeatedly

If new Outlook asks for your password every time you try to add the SharePoint calendar, your Microsoft 365 session may have expired. Sign out of all Microsoft 365 apps, restart Outlook, and sign in again. You can also clear the credential cache in Windows by going to Control Panel > Credential Manager > Windows Credentials and removing any entries that contain “MicrosoftOffice” or “SharePoint”. After removal, restart Outlook and retry the steps.

Calendar events are not updating in Outlook

The SharePoint calendar sync in new Outlook refreshes automatically every few minutes. If events added or modified on SharePoint do not appear in Outlook, force a sync by restarting Outlook. Alternatively, remove the calendar from Outlook and add it again. To remove it, right-click the calendar name under “Shared calendars” in the left pane and select “Remove”. Then repeat the steps to add it from SharePoint.

Classic Outlook Internet Calendar vs New Outlook SharePoint Sync: Key Differences

Item	Classic Outlook Internet Calendar	New Outlook SharePoint Sync
Connection method	Manual paste of .ics URL from SharePoint	Direct connection via SharePoint “Add to Outlook” button
Sync direction	One-way (SharePoint to Outlook)	One-way (SharePoint to Outlook)
Calendar location in Outlook	Under “Other calendars” as an internet calendar	Under “Shared calendars”
Supported Outlook version	Classic Outlook 2016, 2019, and Microsoft 365 classic	New Outlook for Windows (Microsoft 365 only)
Edit events in Outlook	Not supported	Not supported
Requires SharePoint Online	No (works with on-premises SharePoint)	Yes (SharePoint Online only)
Authentication	Windows authentication or prompted credentials	Microsoft 365 modern authentication (OAuth 2.0)

Classic Outlook also supported adding a SharePoint calendar by right-clicking “Other calendars” and selecting “Open Calendar > From Internet”. This method is removed in new Outlook. Organizations still using classic Outlook should plan to migrate to the new SharePoint sync workflow before Microsoft disables the classic internet calendar feature entirely.

You can now replace classic connected SharePoint calendars in new Outlook by using the “Add to Outlook” button directly from the SharePoint site. This method uses modern authentication and does not require manual URL copying. To verify the sync is working, add an event on the SharePoint calendar and confirm it appears in Outlook within one to two minutes. For advanced management, consider using Power Automate to create bidirectional sync flows between SharePoint lists and Outlook calendars if your team needs write-back capability.