The update focuses on improving overall stability.
It has only been a little while since the HTC One M8 came out and now we are already hearing about its second firmware update. The very first update was only for the versions with no Extreme Power Saving mode to help them speed up and now the second update can be considered the actual update because this focuses on improving overall stability.
The existence of the update has already been confirmed by a number of sources including European markets such as UK and Germany and according to them all the update is weighing at just under 70MB and it's available over the air. Though the phone itself is perfect and quite stable right out of the box but these updates show how HTC is constantly taking care of its device and its performance.