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This article describes an update that makes time zone and daylight saving time (DST) changes in Windows. Before you install this update, see the Prerequisites section.

This update applies to the following operating systems:

  • Windows Server 2012 R2

  • Windows 8.1

  • Windows RT 8.1

  • Windows Server 2012

  • Windows Embedded 8

  • Windows Server 2008 R2 Service Pack 1 (SP1)

  • Windows 7 SP1

  • Windows Server 2008 Service Pack 2 (SP2)

  • Windows XP Embedded

Note To get the update for Windows 10 and Windows Server 2016, install the latest cumulative updates that are listed in the Windows 10 and Windows Server 2016 update history page.

Changes by location

Northern Cyprus

Northern Cyprus set its clocks back one hour for daylight saving time (DST) on October 29, 2017, after making no DST changes for the past year. We recommend that all users change their time zone setting from "Istanbul" to the new "Athens, Bucharest" entry.

Time zone key name

Old time zone

New time zone

GTB Standard Time

(UTC+03:00) Istanbul

(UTC+02:00) Athens, Bucharest


The Republic of Sudan switched from UTC+03:00 to UTC+02:00 on November 11, 2017. To accommodate this change, a new time zone was created.

Time zone key name

New time zone

Sudan Standard Time

(UTC+02:00) Khartoum


The Kingdom of Tonga cancelled its DST observance this year. DST was previously scheduled to start on November 5, 2017. DST is no longer observed in Tonga.

Time zone key name

Display name

Old DST start date

Tonga Standard Time

(UTC+13:00), Nuku'alofa Island

November 5, 2017


Update information

The update that is described in this article makes changes in the time zone setting for The Republic of Sudan and in the DST settings for Northern Cyprus and the Kingdom of Tonga.

For more information about how DST changes may affect other Microsoft products, go to the following Microsoft website:

General information about DST

For more information about how DST changes may affect other Microsoft products, click the following article number to go to the article in the Microsoft Knowledge Base:

914387 How to configure daylight saving time for Microsoft Windows operating systems

Note When you apply this update, you may receive a message that resembles the following:

Update cannot be installed as a newer or same time zone update has already been installed on the system.

This message indicates that either you have already applied the correct update or Windows Updates or Microsoft Update has automatically installed this update. No additional action is required to update the Windows operating system.


Learn about the terminology that Microsoft uses to describe software updates.

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