We've been warned that WMF 3 and WMF 4 are incompatible with certain Server applications, such as:
IMPORTANT: Not all Microsoft server applications are currently compatible with WMF 4.0.
Before installing WMF 4.0, be sure to read the WMF 4.0 Release Notes.
Specifically, systems that are running the following server applications should not run WMF 4.0
at this time:
•System Center 2012 Configuration Manager (not including SP1)
•System Center Virtual Machine Manager 2008 R2 (including SP1)
•Microsoft Exchange Server 2013, Microsoft Exchange Server 2010 and Microsoft Exchange Server 2007
•Microsoft SharePoint 2013 and Microsoft SharePoint 2010
•Windows Small Business Server 2011Standard
This is from October 2013.
There can and have been compatibility updates to these packages, but they take time. This note from November 2013 shows how picky some of these applications can be:
The current version of Exchange Server actually requires WMF 3.0, but supports nothing earlier, and nothing later.