A key Microsoft platform differentiator was silently killed by one of the software giant’s biggest partners this week, as Facebook discontinued support for a key API. That means that many Windows, Windows Phone, Outlook.com/OneDrive, Office 365, and Outlook/Office users can no longer sync or share contacts, calendars and other information with Facebook, the world’s most popular social networking service.

Most alarming? There’s no fix. And no fix is coming.

Microsoft started down this integration path with the release of Windows Phone in 2010, and since then, it has added similar services integration functionality to Windows 8 and newer, Outlook (part of Office), Outlook.com and OneDrive, and other relevant platforms. The idea was to let users consolidate all of their information in single end points, so they wouldn’t need to launch different mobile apps to perform different tasks.

This integration was good for users, but it was bad for brands, and Microsoft started stepping back from its integration plans in more recent versions of Windows Phone and Windows, in particular, so that users coming from Android or iOS would experience something more familiar. But integration of contacts and calendar information has remained because of its obvious usefulness.

For Facebook, that integration is over: it has silently made changes to its Facebook Graph API that break integration with Microsoft’s platforms, and neither firm has plans to fix this.

“Facebook’s Graph API is the tool that we use to connect your Microsoft account to Facebook,” a Microsoft support note explains. “It brings contact information from your Facebook friends into Outlook.com and the Windows People app, keeps those contacts up-to-date, and provides options in apps and services like Photo Gallery, Movie Maker, and OneDrive.com to share to Facebook. We collectively refer to these features as Facebook Connect. Due to these changes, Facebook Connect features will no longer be supported.”

The results are pretty disastrous. You will no longer see your Facebook contacts in the People app in Windows, Windows Phone or Outlook.com. Facebook calendar events will no longer sync to Microsoft’s calendar app and services. You can’t share via Facebook with the Share charm in Windows 8 anymore. You can’t publish photos to Facebook from OneDrive. And so on.

The good news? If you’re on Windows Phone 8.1 only, you can install the Facebook app to enable this integration.

For Facebook, this effort is part of a wider strategy to keep its billion-plus users in the Facebook ecosystem, and using its growing collection of branded mobile apps. Facebook wants people to use Facebook apps to keep up with and share with friends, not Microsoft or other apps. But with Microsoft already scaling back its integration ambitions, this move is the final nail in the coffin, and while you can expect its email, calendar, contacts and other solutions to continue to work with various services as is possible, one of the biggest of all services won’t be among them.

Tagged with Facebook, OneDrive, Outlook.com, Windows 8.1, Windows Phone 8, Windows Phone 8.1