Microsoft Security Essentials is not compatible(supported) on Windows Server 2012 R2, however there is a workaround to get it installed:

  1. Download MSE from Microsoft: http://windows.microsoft.com/en-us/windows/security-essentials-all-versions
  2. Rightclick on “mseinstall.exe”
  3. Click on Properties
  4. Click on the “Compatibility”-tab
  5. Check “Run this program in compatibility mode for:”
  6. Select “Windows 7″
  7. Open a Command prompt as Administrator
  8. Run “mseinstall /disableoslimit”

 

w12r2

 

 

 

If windows update later on fails updating MSE, you can redo the process above and it will upgrade your windows essentials. You don’t need to uninstall it inbetween.