Get the date-time of last windows shutdown event using .NET

Question

Is there a way to find out when the system was last shutdown?

I know there's a way to find out last boot up time using the LastBootUpTime property in Win32_OperatingSystem namespace using WMI.

Is there anything similar to find out last shutdown time?

Thanks.

Answer 1

Assuming Windows is shutdown smoothly. It stores it in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows\ShutdownTime

It is stored as an array of bytes but is a FILETIME.

While there may be a better way, I have used this before and think it works:

    public static DateTime GetLastSystemShutdown()
    {
        string sKey = @"System\CurrentControlSet\Control\Windows";
        Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(sKey);

        string sValueName = "ShutdownTime";
        object val = key.GetValue(sValueName);

        DateTime output = DateTime.MinValue;
        if (val is byte[] && ((byte[])val).Length == 8)
        {
            byte[] bytes = (byte[])val;

            System.Runtime.InteropServices.ComTypes.FILETIME ft = new System.Runtime.InteropServices.ComTypes.FILETIME();
            int valLow = bytes[0] + 256 * (bytes[1] + 256 * (bytes[2] + 256 * bytes[3]));
            int valTwo = bytes[4] + 256 * (bytes[5] + 256 * (bytes[6] + 256 * bytes[7]));
            ft.dwLowDateTime = valLow;
            ft.dwHighDateTime = valTwo;

            DateTime UTC = DateTime.FromFileTimeUtc((((long) ft.dwHighDateTime) << 32) + ft.dwLowDateTime);
            TimeZoneInfo lcl = TimeZoneInfo.Local;
            TimeZoneInfo utc = TimeZoneInfo.Utc;
            output = TimeZoneInfo.ConvertTime(UTC, utc, lcl);
        }
        return output;
    }