A couple weeks ago it seems something has changed in the way Facebook Events sync to Windows Phone 7′s calendar. This caused many issues with Windows Phone’s Facebook sync. You can tell if you have the problem by going to Settings > Email+Accounts and you’ll see an “Attention Required” note under your Facebook account which will then list off Error Code 83CF1109. If you hadn’t set up Facebook Chat on your phone before this error started appearing, then you will not be able to get Facebook chat to work with the Messaging app either.
Searching the internet you’ll find many proposed solutions that don’t work including removing the Facebook account from your phone, removing “Microsoft Live” from the apps authorized to access your Facebook account (in Facebook), removing Facebook from your Windows Live Profile, and hard resetting your phone… in any variety of consecutive orders.
Over at the Microsoft Answers forum, many users had become quite frustrated with this problem (myself included). With some collaborative trial and error each failed attempt lead to another idea and as we narrowed the problem down, one user finally found the fix.
It turns out that something changed with the way Facebook events work and how Windows Phone syncs them to your calendar. The problem is the “past events” that you were invited to but never responded to. That’s what’s causing the sync to break.
The work-around to get your Facebook events to sync again is to log into Facebook on your PC, go to Events. Then click the search icon at the top and switch to “Past Events”. Press the “Decline” button next to each one that you did not attend (and still has a “Decline” button showing.) Try to decline at least a couple months worth of old events.
Now when you go back to Settings > Email + Accounts on your Windows Phone, tap & hold on your Facebook account, choose sync, and the error message should go away and all of your upcoming Facebook events should load into your calendar.
Were you recently affected by this sync error on Windows Phone? Did the above work-around fix it? Hopefully Microsoft can work with Facebook to get the sync working properly again so that we don’t need the work-around.
Source: Microsoft Answers forum