Lync Server Installation Error: Prerequisite installation failed: Wmf2008R2

Execute :

%systemroot%\system32\dism.exe /online /add-package /packagepath:%windir%\servicing\Packages\Microsoft-Windows-Media-Format-Package~31bf3856ad364e35~amd64~~6.1.7601.17514.mum /ignorecheck

Reboot puis relancer l'installation.