The Windows 10 Mobile Build 10080 brought Windows 10 Mobile Preview to all the Lumia devices and also to the first non Lumia device HTC One for Windows. But Lumia 640 owners with GDR2 versions 8.10.15217 or higher were out of luck and were not able to update. Same goes for HTC One for Windows users. But this seems have been resolved and now Lumia 640 and HTC One for Windows owners should be able to update to Windows 10 Mobile Build 10080.
#WindowsInsiders with Lumia 640 or HTC One running GDR2 – we now have an upgrade hop for you to build 10080 so you can install.
— Gabriel Aul (@GabeAul) May 21, 2015
You can read full coverage of Windows 10 Mobile Build 10080 by clicking here.