The daylight saving time period ends early after applying a Windows cumulative time zone update

This article describes an issue that may occur after you have installed the latest Windows cumulative Time Zone Update on a client that is running Microsoft Windows or a server that is running Microsoft Windows Server. The behavior includes the time change associated with the end of daylight saving time occurring on the wrong date. Microsoft has determined that this issue will not affect all updated systems in an enterprise. Enterprise customers should use of the three remediation methods described in this article if this issue should occur.

After you install the latest Windows Cumulative Time Zone Update on a client computer that is running Microsoft Windows or a server that is running Microsoft Windows Server, the daylight saving time (DST) period may end earlier than expected. This typically will not affect all updated computers in an enterprise network.

For more information about the latest time zone update, click the following article number to view the article in the Microsoft Knowledge Base:

To work around this issue, use one of the following methods:

Method 1: Temporarily change the time zone for the computer

If you have permission to modify the computer's system clock, follow these steps:

1. Click Start, click Run, type TimeDate.cpl and then click OK.
2. Click the Time Zone tab.
3. Note the current time zone, and then select a different time zone from the list of time zones.
4. Click Apply.
5. Select the original time zone from the list of time zones and then click OK.

Method 2: Use a command-line statement to refresh time zone information on computers in a single time zone

If the user does not have access to the system clock, the following method can be used to push the time zone update to multiple clients:

Note This method requires that the command that is described below be run under the security context of a user in the local Administrators group. Additionally, this method assumes that you know the name of the time zone in which the client computer resides. If you have clients in multiple time zones, use method 3.

• Add the following statement to a logon script or batch file:
  

  control.exe timedate.cpl,,/Z Time_Zone_Name

  For example, if the client computer uses Eastern Standard Time, you would use the following:
  

  control.exe timedate.cpl,,/Z Eastern Standard Time

Method 3: Use a VBScript to refresh time zone information on computers in multiple time zones

If the user does not have access to the system clock, the following method can be used to push the time zone update to multiple clients:

1. Click Start, click Run, type notepad, and then click OK.
2. Copy the following code, and then paste it into the Notepad document:

   Set objSh = CreateObject("WScript.Shell")
   
   'Get the StandardName key of the current time zone
   szStandardName = objSh.RegRead("HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\StandardName")
   
   'Enumerate the subkeys in the time zone database
   const HKEY_LOCAL_MACHINE = &H80000002
   Set objReg=GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\default:StdRegProv")
   szTzsKeyPath = "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
   objReg.EnumKey HKEY_LOCAL_MACHINE, szTzsKeyPath, arrTzSubKeys
   
   'Step through the time zones to find the matching Standard Name
   szTzKey = "<Unknown>"
   For Each subkey In arrTzSubKeys
       If (objSh.RegRead("HKLM\" & szTzsKeyPath & "\" & subkey & "\Std") = szStandardName) Then
           'Found matching StandardName, now store this time zone key name
           szTzKey = subkey
       End If
   Next 
   
   If szTzKey = "<Unknown>" Then
          'Write entry to the Application event log stating that the update has failed to execute
          objSh.LogEvent 1, "DST 2007 Registry Update and Refresh failed to execute on this computer.  Time zones failed to enumerate properly or matching time zone not found."
          Wscript.Quit 0
   End If
   
   Dim process, processid, result, strUpdateCommand
   Set process = GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\cimv2:Win32_process")
   
   'Add time change privilege to the process object
   process.Security_.Privileges.AddAsString "SeSystemTimePrivilege",True
   strUpdateCommand = "control.exe timedate.cpl,,/Z" & szTzKey
   
   'Launch control.exe to refresh time zone information using the TZ key name obtained above 
   result = process.create(strUpdateCommand,Null,Null,processid)
   If result <> 0 Then
        objSh.LogEvent 1, "DST 2007 Registry Update and Refresh failed to execute on this computer.  Unable to refresh the Timezone database."
       Wscript.Quit 0
   End If
   
   'Get current display name of refreshed time zone
   szCurrDispName = objSh.RegRead("HKLM\" & szTzsKeyPath & "\" & szTzKey & "\Display")
   
   'Write entry to the Application event log stating that the update has executed
   objSh.LogEvent 4, "DST 2007 Registry Update and Refresh has been executed on this computer." & chr(13) & chr(10) & chr(13) & chr(10) & "Current time zone is: " & szCurrDispName & "."
   

3. On the File menu, click Save As.
4. Select a destination, and then type refreshTZinfo.vbs in the File name box.
5. In the Save as type box, click All Files, and then click Save.

For more information and for an exact example of how to deploy this VBScript, click the following article number to view the article in the Microsoft Knowledge Base:

Verify that the change was made

To verify that the workaround method worked correctly, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following subkey in the registry:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation
3. Note the StandardName value.
4. Note the StandardStart value.
5. Note the DaylightStart value.
6. Exit Registry Editor.
7. Using the StandardName value as the time zone name, compare the values for StandardStart and DaylightStart to the values that are listed in the following table. This is representative of the correct StandardStart and DaylightStart values from the latest Windows Cumulative Time Zone Update.

For more information about the latest Windows Cumulative Time Zone Update, click the following article number to view the article in the Microsoft Knowledge Base: