The April Cumulative Update for SharePoint 2013 (both Foundation and Server) are available for download since 26th of April.
Starting SharePoint 2013 the link to the site where download could be “ordered” (yes, because for a while now you need to specify your business email in order to get the proper download link) is to use SharePoint CA, under Upgrade and Migration > Check product and patch installation status page right on top there is the link heading out to http://go.microsoft.com/fwlink/?LinkId=160585
There are many ways to find current version of your farm. Via SP-CA use the Server > Servers on Farm (<Your Farm Central Admin URL>/_admin/FarmServers.aspx)
or if you prefer Powershell via the SharePoint 2013 Powershell console (Run as Administrator) and use
$farm = Get-SPFarm $farm.BuildVersion
- RTM Farm version is 15.0.4420.1017
- With March 2013 CU - 15.0.4481.1005
- After installing April 2013 CU is 15.0.4505.1005
As you are aware by now, the March 2013 Cumulative Update is mandatory prior to any update! You’ll find that here http://support.microsoft.com/kb/2726992
As for the April Cumulative Update :
- SharePoint Foundations 2013 http://support.microsoft.com/kb/2751999
- SharePoint Server 2013 this is available at KB2726992 http://support.microsoft.com/kb/2726992
- If you are running SharePoint Server 2013 you do not need to install the Foundations CU prior to the Server CU.
- You still need to run the SharePoint Configuration Wizard to finalize the upgrade (fail to do so and you shall experience strange behaviors, e.g. search not starting, etc)
- User Profile Synchronization would not start – you need to do that manually after all is done (you would need the password for the farm service account)
- As an old friend of mine once said: “When in doubt – have a restart” – basically do perform a reboot after installing just to be safe.