Build 1507 of the OS was to exit support on the 26th March, but Microsoft has now announced on Technet that version 1507 will continue to be serviced until May 2017.
Currently Microsoft plans to only support the two latest versions of Windows 10, and expect most users to remain current with the latest version of the OS via automatic updates, a practice which has been criticised but which means that more than 75% of Windows 10 users are on the latest public version of the OS.



