Recently, Microsoft blocked updates for devices with certain newer processors, for more information, read this news article. If your PC is affected, a developer, "zeffy" has discovered that modifying a file called "wuaueng.dll", within the file there are two functions, 'IsDeviceServiceable(void)' and 'IsCPUSupported(void)'. The developer has stated two ways to prevent the CPU update lock:
Patch wuaueng.dll and change dword_600002EE948 (see this line) which is at file offset 0x26C948, from 0x01 to 0x00. This makes IsDeviceServiceable(void) jump over its entire body and return 1 (supported CPU) immediately. This is my preferred method. Note: this offset is only for the KB4012218-x64, for a list of all the patch offsets click here.
Patch wuaueng.dll and nop out all the instructions highlighted here in IsDeviceServiceable(void), this will enable the usage of the ForceUnsupportedCPU of type REG_DWORD under the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Test\Scan (you will most likely have to create this registry key). Set this value to 0x00000001 to force unsupported CPUs, and back to 0x00000000 to change the behaviour back to default. You will probably need to restart your PC or restart the wuauserv service in order for changes to apply. This behaviour is an internal test feature used by Microsoft and could be removed in future updates, so I will not be providing xdelta files for it.
If you'd like, the patch can be downloaded here.
Notes:
You have to apply a new patch whenever wuaueng.dll gets updated
SFC scan errors will most likely occur as it will believe the integrity of the system has been compromised since a system file was modified