One or more items in the folder you synchronized do not match
The error message "one or more items in the folder you synchronized do not match" indicates that Outlook has conflicting items that it cannot resolve on its own. You will need to open Outlook, find these items, and resolve them manually.
To resolve this issue
First, open the area in Outlook that had the error message and perform the following steps. If you do not know which area this is, please repeat the steps for each area of Outlook (Contacts, Calendar and Tasks):
- Change the Current View to View by Category; you will see a list of categories
- Click on the plus sign to the left of the category name to view the items in the category
- You will see an icon to the left of each item; look down the list of items for a "crossed-swords" icon or other warning icons
- Double-click each item that has one of these items to resolve the problem