Japanese calendar era bug

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The Japanese calendar era bug is a possible computer bug related to the change of Japanese era name.


The Japanese calendar has Japanese era names that changes with the reign of the Japanese emperor. Since most of the modern age of computing has occurred in the Heisei era, much of the software developed in this era only has support for era names during the Heisei era.[1]

A new era name was expected with the forthcoming 2019 Japanese imperial transition. However, since the change of eras is infrequent, most software has not been tested to ensure that it will behave correctly with an additional era. Computer and software manufacturers need to test their systems prior to the transition in order to ensure that the new era will be handled correctly. In order to ensure this, some systems provided test mechanisms to simulate a new era ahead of time.[2]

In early April 2019, the new era name was announced to be Reiwa for "beautiful harmony."

Documented errors[edit]

Some minor problems have been reported due to improper handling of the era transition.

  • ATMs placed inside the Lawson chain of konbini reported that due to a banking holiday funds deposited would not be available until May 7, 1989, due to a date conversion improperly using Heisei 1 (1989) instead of Reiwa 1 (2019).[3]

Planned fixes[edit]

  • Windows 10 Spring Release includes a registry entry with placeholder information for the expected era transition, intended to help users discover any software limitations around the expected change to the new era.[2]
  • Unicode code point U+32FF has been reserved in September 2018 for representing the new era name[4] and Unicode 12.1 finally includes the U+32FF character for Reiwa.[5]
  • The GNU C Library patch will be included in the 2.30 release.[6]

See also[edit]


  1. ^ "Era Handling for the Japanese Calendar - Windows applications". docs.microsoft.com. Retrieved 2019-01-31.
  2. ^ a b "The Japanese Calendar's Y2K Moment".
  3. ^ Baseel, Casey (30 April 2019). "ATMs in Japan are saying they'll transfer your money back in time to 1989". SoraNews24. Retrieved 30 April 2019.
  4. ^ "New Japanese Era". Retrieved 2019-01-31.
  5. ^ "Unicode 12.1.0". Retrieved 2019-05-01.
  6. ^ "22964 - The Japanese Era name will be changed on May 1, 2019". Retrieved 2019-05-01.