If you have any WMF 4.0 Preview or earlier versions installed, they must be removed before proceeding. Step-by-Step Download and Installation Determine installed PowerShell version
You must have .NET Framework 4.5 or higher installed. download powershell 4.0 for windows server 2012
Before installing the WMF 4.0 update, ensure your system meets these requirements: If you have any WMF 4
Windows Server 2012 Standard or Datacenter (not R2). download powershell 4.0 for windows server 2012
To for Windows Server 2012 (non-R2), you must install the Windows Management Framework (WMF) 4.0 package. While Windows Server 2012 R2 comes with version 4.0 pre-installed, the original Windows Server 2012 ships with version 3.0 and requires a manual upgrade. Prerequisites for Installation