Earlier this evening, Microsoft released Windows 10 Mobile Build 101512 to Windows Insiders on the fast ring. If you’re already using Windows 10 Mobile, you should be able to upgrade to Build 10512 without any issues. However, if you’re trying to upgrade from Windows Phone 8.1, you’ll have to upgrade to Build 10166 first, and then upgrade to 10512. A Windows Insider asked Microsoft’s Gabriel Aul on Twitter about this issue, and he confirmed that you can’t directly upgrade to Build 10512 from Windows Phone 8.1:
It’s worth noting that we’re not quite sure if Microsoft will be fixing this issue sometime soon. However, for now, if you want to upgrade to the latest Windows 10 Mobile build from your Windows Phone 8.1 device, you’ll have to upgrade to Build 10166, and then upgrade to Build 10512.
Have you tried upgrading from Windows Phone 8.1 to Build 10512? Let us know in the comment section below.