— Gabriel Aul (@GabeAul) January 23, 2015
Microsoft recently released an update for Windows 10 Technical Preview Build 9879 (KB3025380). This update includes improvements to Windows 10 Technical Preview Build 9879 that will let members of the Windows Insider Program continue to receive future released builds of Technical Preview.
If you have installed leaked build Windows 10 Build 9901, then you will not get the next preview build through Windows update due to a bug. Microsoft is advising those users to use upcoming Windows 10 build ISO to update their systems.
Find more details on it here.