It seems that the KitKat update brought along with it a major issue where the Wi-Fi no longer functions. Half way through the update, HTC ceased the roll out.
Today, the update is back live again and this time, the issues have been fixed. There is a new build number to the KitKat and it is 4.19.401.11. This latest OS update can be obtained OTA for the international version.
It is unsure to when the carrier-update will be released but UK carriers Vodafone, O2 and Three are confirmed to be giving away the update.
If you’re a HTC One user, you can check for the updates by going to Settings> About Phone> Software Update> Check Now.