Build 9909, however, was never meant to be a public-facing milestone. It was an internal "fbl_impressive" (FBL meaning Feature Build Lab) build, meaning it was where Microsoft tested radical, potentially unstable features. When it leaked, it broke the illusion that Windows 10’s development was linear.
Warning: This build is timebombed. It expired on October 1, 2015. To run it, you must either set your VM’s BIOS date to December 2014 or use a patched windload.efi / winload.exe . Legally, this build is abandonware, but Microsoft’s EULA technically forbids distribution. Proceed at your own risk. windows 10 build 9909