The VP of Product Management at HTC, Mo Versi, today announced through Twitter that the Android 6.0 Marshmallow update for the Sense variant of the One M8 will start rolling within the next 24 hours.
The update will initially be rolled out to the unlocked variant of the handset in the U.S., with carrier versions getting the update in the first quarter of 2016 after getting the necessary approvals and certifications from carriers.
HTC One (M8) unlocked owners! Great news, all testing has been complete and the update for Marshmallow will be sent out within 24 hours. Thx
— Mo Versi (@moversi) December 2, 2015
As for the One M9, Mo replied to tweets from some customers and said that the company is still on track to roll out the update by the end of this year for the device. This was for the Verizon variant of the handset, so presumably the update for the unlocked variant will also be rolled out around that time.
It is likely that HTC will expand the roll out of the Marshmallow update for the Sense running One M8 to Europe and other regions of the world before the end of this year.
HTC had previously updated the Google Play edition variant of the One M8 to Marshmallow in early November. With the One M9 already running Marshmallow out of the box, the company now has more devices in the market running the latest version of Android than any other OEM except Google.