HTC has started rolling out Android 6.0 Marshmallow update for HTC Desire 816 users. The update is an over-the-air one currently rolling out to users in Saudi Arabia but some users in India have also claimed to have received the update a few days back.
The update brings Sense UI version 7.0 with build No 3.12.401.2. It is being rolled out in two parts, the first being around 55MB in size, while the second weighs in at over 1GB. The former prepares your device for Marshmallow, and the latter actually installs the Android 6.0.
Keep checking you phone for the updated OS as over-the-air updates are generally rolled out in phases. You can manually check availability of the new software by going to Settings>About phone> System updates> Check For Update.
Just a few days ago, HTC rolled out the Marshmallow update for Desire EYE, One E8 and One M8 Eye users in China and Europe. HTC users in the US need to track their operators as most OS updates are carrier-specific there. Android Authority reported recently that HTC has already started rolling out the Android 6.0 Marshmallow for the Desire 816 on Sprint, T-Mobile, AT&T, and Verizon in the US.
The company has so far seeded the latest firmware to One M9, One M8 Dual SIM and One A9. HTC has not disclosed when older devices like the Butterfly 3, Desire 826 and Desire 820 will receive the latest Android update or whether they will receive the update at all.