Today HTC is rolling out Android 6.0 to HTC Desire 820 in Europe. According to sources, ROM version is 2.11.401.6. and the update will roll-out in two parts.
The HTC Desire 820 is powered by 1GHz octa-core Qualcomm Snapdragon 615 processor and it comes with 2GB of RAM. The HTC Desire 820 is a dual SIM. Android 6.0 will include many new features like Google Now On Tap, App permissions, smart battery Optimization doze and many more.
— Robin Weißenborn (@robinwe97) May 3, 2016
You can see full Android 6.0 update eligible devices list & update release dates By clicking here.