As HTC had promised, it has already released Android 6.0 Marshmallow update for its older flagship models like HTC One M9 and One M8. Currently, it is in the process of releasing Android 6.0 upgrade to other HTC smartphones.
HTC One A9
The unlocked HTC One A9 has received the latest Android 6.0.1 update. The 6.0.1 Marshmallow update is an incremental build that brings 200+ emojis and some performance improvements over 6.0 version.
HTC One M9
HTC One M9 users on T-Mobile, Sprint and Verizon have received the Android 6.0 build at the start of March. AT&T has not released the latest Android firmware yet for its HTC One M9 users. The unlocked HTC One M9 has already received Android 6.0 update at the end of last year.
HTC One M8
In December 2015, HTC had released Android 6.0 upgrade for unlocked HTC One M8 users. In the U.S., Verizon and T-Mobile has released Android M update for HTC One M8 users at the start of this month. In November last year, the Android M update was made available to HTC One M8 GPE users.
HTC One E8 and HTC One M8 Eye
Users of HTC One E8 and One M8 Eye in China are currently receiving Android 6.0 Marshmallow update. Rumors suggest that other variant of these smartphones are expected to receive the latest Android firmware at the end of March.
HTC Desire Eye
HTC Desire Eye was not listed in the in the original list of eligible devices for Android Marshmallow update. The smartphone that was released in October 2014 is now receiving Android 6.0.1 Marshmallow update along with HTC Sense 7.0 UI in regions like UAE and Italy, Phone Arena reported. In the U.S., AT&T Desire Eye is expected to receive the software update at the end of this month.
Some of the other HTC smartphones that are speculated to receive Android 6.0 Marshmallow upgrade include HTC One M9+, One E9+, One M9, One ME, Butterfly 3, Desire 826, Desire 820 and Desire 816. The list of Android 6.0 compatible devices does not include the HTC One M7 smartphone. The upcoming HTC One M10 (aka HTC 10) is expected to release with Android 6.0.1 Marshmallow and HTC Sense 8.0 UI.