Hello,
In your case, Symantec Endpoint Protection must be completely uninstalled before upgrading the operating system. This applies to all versions of SEP. Upgrading the operating system with SEP still installed is currently unsupported due to potential issues which may arise during the upgrade.
After the operating system is migrated, SEP 12.1 may be reinstalled. Check this Article:
Should Symantec Endpoint Protection be uninstalled from the computer before upgrading Microsoft Windows to a newer version of Windows?
http://www.symantec.com/docs/TECH197095
Symantec 12.1.2012 is fully supported on Windows Server 2012. However, it is always advisable to install the Latest version of SEP 12.1 (i.e; currently the Latest version is SEP 12.1.3001) on your environment.
About Windows 8 and Symantec Endpoint Protection 12.1
http://www.symantec.com/docs/TECH174348
Hope that helps!!