Code of Matt

Windows Registry Patch for Egypt 2016 Cancellation of DST

Matt Johnson-Pint -

As you may know if you follow my blog, I previously wrote about the recent time zone chaos in Egypt.  In this post I'd like to offer some guidance on what to do about it.

On Microsoft Windows desktop or server operating systems, you may find that the time will automatically change on the morning of Friday, July 8th.  This is because Microsoft issued KB3162835 in June which reflected the Egyptian government's previous decision to enact DST from July 8th through the end of October.  If you are applying automatic Windows updates, or getting the monthly builds of Windows 10, then you likely have this on your system already.  (An easy way to tell is to check if any of the newly added zones mentioned in the KB are present in the list of time zones on your system settings or control panel.)

Unfortunately, there simply isn't enough time between the date that the government changed their mind and the previous effective date for Microsoft to create, test, and distribute another update to retract this.  Microsoft is working on an update to release in the near future, but the availability date is uncertain at this time.  Meanwhile, many computers will reflect the time in Egypt inaccurately.

Microsoft's official guidance on this matter recommends two possible options:

  • You can leave the time zone set for Egypt, and disable automatic daylight saving time via the Windows 10 settings page, or via the date and time control panel in previous versions of Windows.  This should be the preferred action for most desktop Windows users. The same thing can be done from the command line with:  
tzutil /s "Egypt Standard Time_dstoff"
  • You can select a different time zone to set your computer to either (UTC+02:00) Harare, Pretoria, or (UTC+02:00) Tripoli. Neither of these use daylight saving time in 2016.  This is a good option for those on Windows Phone 10 devices, which do not have an option for disabling DST. Note that earlier versions of Windows Phone did not receive the June DST update, so they do not need to be changed at all.  

These are both great options, and are the only official recommendations from Microsoft.  However, they do not cover all possible uses of time zone information.  Other common uses include:

  • Application servers running .NET applications that rely on the TimeZoneInfo class to provide accurate time for multiple time zones within a custom application.
  • Exchange Servers that need to reflect times correctly in Outlook Web Access.
  • Large organizations that need to correct time across many desktops and servers across their network.

For these scenarios, and many others, it makes more sense to correct the underlying Windows Registry data for the Egyptian time zone.  I have created a .REG file for this purpose, which you can download here.  Running this file on your system will correct the time zone information for Egypt Standard Time, removing the DST information for 2016, and canceling it for all future years as well.  DST information for 2015 and prior is left intact.  It is designed to be ran on Windows Vista and newer operating systems only.

Please note that this file is is an UNOFFICIAL and UNSUPPORTED patch, provided "AS-IS" by myself, Matt Johnson, independently of any activities of Microsoft.  While I do work for Microsoft, I do not work in the Windows group, and this is not a Microsoft product or supported solution.  Examine the registry file for yourself before making the decision on whether to apply it to your computers.  While I am confident that it will cancel DST for 2016 on your computers, I take no responsibility for any effects or side effects it may have.

If you're running a desktop operating system other than Windows, or any platform that uses the IANA time zone database, you can probably just update your tzdata distribution to 2016f, announced here.  However, for phones running iOS and Android, unfortunately you may have to wait for a system update to get the Egyptian time zone fixed.  Consider using the time zone of South Africa or Libya in the meantime.

If you have any questions about this, please ask in comments below.  I hope this helps a few people out there work around this issue until an official update can be provided.

The current time in Egypt is shown below.  If the time on your clock is showing an hour ahead, then you need to disable DST, choose a different time zone, or update your system.