Windows 10 build 9841 (fbl release)

Windows 10 build 9841 is a build of Windows 10. It was demonstrated by Microsoft on 2014-09-30 at a closed press conference and released as a Technical Preview the next day, on 2014-10-01.

It is the first publicly available build of Windows 10, released to users who joined the Windows Insider program.

Installation
If you're installing this build, you must either change the host PC's time to the BIOS date time listed (2014-09-13) for the case of virtual machines or turn off all network adapters even if you turned off the time sync and set the BIOS date for the machine, otherwise after the hardware setup it will automatically adjust to the current time via online time syncing and activate the timebomb, instantly breaking the build and the bootloader.

Media Center
If you add Windows Media Center to this build using a purchased Windows 8.1 product key, the system subsequently identifies itself as running "Windows 8.1 Pro with Media Center", along with a warning that the OS has not been activated.