I had to stage Core Server with System Center Configuration Manager 2012. Not much changes I thought…
The Agent Version 5 of the SCCM Client requires .Net Framework 4, but no problem, .Net 4 is installed with the client, but for a core Installation you will need a specific .Net Installer. You can find it here:
Now, you have to install the .Net Framework while the Windows Setup is running, because after the Setup, the first step is to install the SCCM Client.
Make sure that you have configured to install the following features in your unattend.xml:
The executable has to be available for the installation, I used to connect a network share and run it from there.