If you own a Windows Phone handset, and you're waiting for Microsoft to update it to Windows 10, we have bad news. Initially, Microsoft believed that it would be able to start rolling out Windows 10 updates for Windows Phone 8.x devices in December, but this will actually not happen.
According to a statement issued today by Microsoft, no Windows Phone 8.x handset will be updated to Windows 10 before early 2016. It's not clear why Microsoft has been forced to delay the update, but that's how things stand: unless you're part of the Windows Insider program, or you have one of the three new handsets that run Windows 10 out of the box (Lumia 950, Lumia 950 XL, or Lumia 550), you won't be able to experience Windows 10 on your phone this year.
When the Windows 10 update is finally released, these are the Windows Phone 8.1 handsets that should be among the first to get it: Lumia 930, Lumia 830, Lumia 735, Lumia 640 XL, Lumia 640, Lumia 540, Lumia 535, Lumia 532, Lumia 435, and Lumia 430.