Tzsync.exe Error: Unhandled Exception (System.IO.IOException)

When you sync the time zone information using the built-in Tzsync.exe tool, an “Unhandled Exception” error occurs.

Application: tzsync.exe
Unhandled Exception: System.IO.IOException: The specified registry key does not exist.
at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)
at Microsoft.Win32.RegistryKey.GetValueKind(String name)
at TimeZoneSyncTask.DynamicDstTransform.GetDynamicDstRange(RegistryKey rkTimeZoneRoot, Dictionary`2 mapWinTzToTzid)
at TimeZoneSyncTask.TimeZoneSync.Sync()
at TimeZoneSyncTask.Program.Main(String[] args)

tzsync.exe unhandled exception

And the following error shows up on the View Reliability History page in the classic Control Panel.

TimeZone Sync Task
Faulting Application Path:	C:\Windows\System32\tzsync.exe

Problem signature
Problem Event Name:	CLR20r3
Problem Signature 01:	tzsync.exe
Problem Signature 02:	6.2.19041.1
Problem Signature 03:	99fdcbd2
Problem Signature 04:	mscorlib
Problem Signature 05:	4.8.4515.0
Problem Signature 06:	624ce856
Problem Signature 07:	133
Problem Signature 08:	72
Problem Signature 09:	System.IO.IOException
OS Version:	10.0.19045.
Locale ID:	1033
Additional Information 1:	cd38
Additional Information 2:	cd383bc96f44aa9dc0e7b57396226585
Additional Information 3:	d62c
Additional Information 4:	d62c082b037d9144b39b68244953838d

Extra information about the problem
Bucket ID:	ffc2d00a5c4e5b4c4117f9aa174b54ff (1231727532039689471)


To resolve the tzsync.exe unhandled exception error, restore the missing Time Zone keys in the registry.

  1. Open an Admin CMD Prompt.
  2. Export your existing Time Zones key to a REG file. To do so, run the following command:
    reg export "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones" c:\tz_backup.reg
  3. Exit the Command Prompt window.
  4. Download timezones.reg (zipped) and run it.
    (This REG file has been extracted from a Windows 10 22H2 computer.)

That should fix the tzsync.exe System.IO.IOException “The specified registry key does not exist” error.

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Ramesh Srinivasan is passionate about Microsoft technologies and he has been a consecutive ten-time recipient of the Microsoft Most Valuable Professional award in the Windows Shell/Desktop Experience category, from 2003 to 2012. He loves to troubleshoot and write about Windows. Ramesh founded in 2005.

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