The first three builds of the Windows 10 Technical Preview will refuse to boot after the end of April, as Microsoft attempts to usher testers towards the latest version of the pre-release operating system. Microsoft has so far released six stable builds of the Windows 10 Technical Preview, although testers on the "Fast Ring" - who receive more experimental versions of the OS - have seen several more.
The first three builds - numbered 9841, 9860 and 9879 - are all set to stop booting on 30 April, giving anybody still running those early versions just a couple of days to upgrade to a more recent build. Those users should already be seeing warnings to upgrade, with their systems rebooting every three hours as an unsubtle reminder to move before the big switch off, according to a schedule acquired by Microsoft News.
Those running builds 9926, 10041 and 10049 will start seeing upgrade warnings from mid-September, the reboots starting on 1 October and the operating system finally expiring and refusing to boot on 15 October.
It's not clear how many more versions of the Technical Preview Microsoft will release before Windows 10 is finally launched. Microsoft has stated that it plans to have Windows 10 with PC manufacturers by the end of the summer, but with only a couple of months of testing time left to hit that deadline, Microsoft is sailing close to the wind. Key features of the operating system, such as the design of the Start menu, the Windows Store, the new Spartan web browser and the Cortana voice assistant are still at a highly experimental stage, and the operating system remains worrying unstable in our tests.
Windows 10 testers can download the latest version of the operating system by going to Settings > Update & Recovery > Windows Update, if their PC hasn't already updated. You can see which build you're running by looking in the bottom right-hand corner of the Windows desktop, just above the clock.