Microsoft has taken the Windows RT 8.1 update offline due to problems in the update process of RT devices.
The company is "investigating a situation affecting a limited number of users updating their Windows RT devices to Windows RT 8.1," and has temporarily removed the Windows RT 8.1 update from the Windows Store. Microsoft said it would provide updates as they become available.
Microsoft did ot provide any additional infrmation, although the issue is reportedly caused some Windows RT to have their boot data damaged during the update.
Windows 8 RT runs on Microsoft's Surface RT tablets.