By now, it has been pretty well-established that Android Version 6.0 (also known as Android M or Marshmallow) has rolled out on a lot of flagship phones form major companies like Samsung, LG, Sony, and Motorola.  In fact, one could say that we are in the last stages of the Android M upgrade as HTC's flagship phones are covered, with only its other One and Desire Android devices unaccounted for.  Here is the latest news on Android M 6.0 Marshmallow Release Date for HTC One M9, the One M8, and the Desire series on Sprint, US Cellular, Verizon, AT&T, and T-Mobile. 

The issue with HTC is that it has just revealed its current flagship with the HTC 10, (not the HTC One M10) and it will have Android 6.0 right out of the box.  As it stands, the HTC One M9, last year's flagship phone, it has all five of its major United States carriers having Android Marshmallow.  Not only that, the flagship from two years ago with the HTC One M8 has received its Android upgrade.  The HTC One M7 won't be getting an Over The Air (OTA) update, but there is a custom ROM for Android 6.0 for those that know how to download it. 

According to Tech Radar, HTC has confirmed that One A9, Desire Eye, and One E9 will get the Android Marshmallow upgrade, but there is no word when it is coming out.  This goes for other HTC phones including: 

• HTC One M9+
• HTC One E9+
• HTC One ME
• HTC One E8
• HTC One M8 EYE
• HTC Butterfly 3
• HTC Desire 826
• HTC Desire 820
• HTC Desire 816

Believe it or not, HTC confirmed all the way back in September of last year that it will be upgrading these devices, but it has been taking so long that it still isn't known when it is coming. 

At this point in time, it might be better to say that since HTC has already established its flagship phone and its flagship phone from two years ago as upgraded, it would appear that the other devices mentioned in the previous bulleted list are of low priority. 

Generally, a good source for HTC upgrades was Mo Versi, and his tweets are usually full of notifications of when the latest version of Android would be coming to HTC devices.  Unfortunately, much of his tweets are focused on the HTC 10, the latest flagship phone. 

So if you have a recent HTC device, it is possible that it has access to Marshmallow already.  So if you happen to be a user of one of these HTC non-flagship devices, you should check your "Settings" and "System Update" to see if you can download the Over the Air (OTA) upgrade now.  It is possible that the upgrade could be available on one carrier for the same phone and yet not on another, which is a pattern in Android rollouts.