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How to resolve unexpected changes in VM time/time-zone in a Windows environment

This issue, which is caused due to the mismatch of the host client system/time settings and the guest time settings, can be resolved in either of these ways:

  1. The cloud VM gets the time from the underlying hardware, which is UTC.

We can now manipulate this from the the Advanced Configuration window of the VM (General Tab - Advanced Configuration). rtc, or Real Time Clock - Sets the timezone for the VM. This is an object containing a string mode and a long number seconds. The possible modes are:

  • ABSOLUTE: Time is configured manually and will not survive reboot.
  • RELATIVE: Sets the relative seconds after UTC and will survive reboot. 

For example, if you need to set Pacific Standard Time, you will put RELATIVE in the rtc-mode box, and -28800 in rtc-seconds, which is -8 hours from UTC

(These settings cannot be changed when the VM is running)



  1. Another approach is to change a registry flag in Windows so that it uses the format we provide. This should also take care of this problem:

START - RUN (run the following command)

reg ADD HKLM\System\CurrentControlSet\Control\TimeZoneInformation /t REG_DWORD /v RealTimeIsUniversal /d 1



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