You have a computer that has 1 gigabyte (GB) memory installed and is running a 32-bit version of Windows 8. When you try to upgrade to Windows 8.1, the upgrade fails, and the system is rolled back to its previous state.
This problem occurs because the upgrade is too large for the random access memory (RAM) that is available on the computer. The RAM that is available is less than 1 GB.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.