Approaching its two year anniversary in March, this should be the last major version of Android that the One M8 will be updated to. HTC is currently in the process of evaluating whether the M8 will get Android 6.0.1. This update brings Sense 7.0, first released on the M9 in March, in addition to other Marshmallow features like Now on Tap, Doze, and a new app permissions model.
The more recent One M9 has yet to receive Marshmallow in the UK, but Canadian carrier models of the device started getting the update on Monday. In the US, Sprint and T-Mobile variants of the M8 are expected to get Android M by the end of the month. The One M9 on AT&T and Verizon will get the update in a “few more weeks”.
We’ve begun rolling out the Android 6.0 Marshmallow update to the One M8. It’ll be coming the One M9 soon, too!— HTC UK (@HTC_UK) January 19, 2016