Earlier today, we reported that Windows 10 Mobile users on the Fast Ring were seeing a new update named “Localization for English” in Windows Update. As it turned out, this update was actually the Windows 10 Mobile Insider build 14998, and it seemed at the time that Microsoft rolled it by mistake. That's why we recommended you not to install it.
A couple of minutes ago, Head of the Windows Insider Program Dona Sarkar just confirmed that this build wasn’t meant to be released to Windows Insiders. The company is still investing why this build has been released to the wild, but Sarkar explained that "you don't need to install this one."
For any #WindowsInsiders who are seeing 14998, we are investigating. You don't need to install this one.
— Dona Sarkar (@donasarkar) January 12, 2017
We're still waiting for more information about build 14998, and we hope that Microsoft will provide a straightforward upgrade path (to be clear, with no need to do a factory reset, or worse) for those of you who installed this update without being aware that it was actually a new build.