Windows 8.1 build 9477 (fbl partner out31)

On 2013-08-09, win8china posted an article about build 9477 being released to partners. It also mentioned that soon, Windows 8.1 will hit RTM Escrow.

On 2013-08-20, a user called by 我爱穹妹 posted two screenshots of this build to PCBeta. One of them revealed most of the buildstring, though he censored the time and hash.

On 2013-08-21, the build leaked on PCBeta. It originally leaked in the form of all folders in one .rar file, and the boot folder was missing. There were various attempts to fix it, most of the times using just the regular 9471 boot folder, but JaGoTu's ultimate 9477 patch uses 9477 files where possible.

On 2018-10-19, the build leaked in many languages, including English.