Unlike iOS, Android has a serious device fragmentation issue. This precipitates itself in a number of different ways.

Multiple platform versions “in the wild” with a significant percentage of unsupported devices
Devices can’t be updated to current versions
Device vendors do not support current software versions even for current hardware

TODO: This should become a tech note.

Things to discuss:

Device adoption levels
The Kitkat v4.4 issue (TSL security), fixed in V4.4.4
Google Mobile Services (GMS) is a collection of Google applications and APIs that help support functionality across devices

A representative list of Android devices can be found on the Xamarin Test Cloud, select the Android

Platform Versions

Data taken from Device uptake (updated fortnightly) & correct at 2017-06-05

Version	Codename	API	Distribution	Supported	Release Date
2.3.3..7	Gingerbread	10	0.8%	No	2010
4.0.3..4	Ice Cream Sandwich	15	0.8%	No	2011
4.1.x	Jelly Bean	16	3.1%	No	2012
4.2.x	-“-	17	4.4%	No	2012
4.3	-“-	18	1.3%	No	2012
4.4	KitKat	19	18.1%	4.4.4 only	2013
5.0	Lollipop	21	8.2%	Yes	2014
5.1	-“-	22	22.6%	Yes	2014
6.0	Marshmallow	23	31.2%	Yes	2015
7.0	Nougat	24	8.9%	Yes	2016
7.1	-“-	25	0.6%	Yes	2016
8.0	O	26	-	Beta	-

NOTE: Platform versions prior to 4.4.4 (The final “.4” is important) are not supported by Google (Approximatly 10% of the userbase)

Fragmentation Chart