The Windows 10 Spring Release includes a placeholder for the era expected to begin on 1 May, 2019. That information is in a registry key that can be removed or edited in the event that a system's software misbehaves with this additional information.
The Japanese Calendar has Japanese Era Names that coincide with the reign of the Emperor. For most of the modern age of computing that has been the Heisei era, however the Emperor is expected to step down on April 30, 2019. Which will bring about the beginning of a new era. Fortunately, this is a rare event, however it means that most software has not been tested to ensure that it will behave with an additional era.