Date time Conversion

Your error is caused by the fact that the fraction-of-a-second part of your date string has more than seven places. If you reduce the number of letters after the seconds to seven, it will work, as you can see here:

// required
using System.Globalization;

private void testConversion()
{
    string date = "2014-11-26 15:46:56.1070000";
    
    string inFormat = "yyyy-MM-dd HH:mm:ss.FFFFFFF";
    string outFormat = "dd/MM/yyyy HH:mm:ss.FFFFFFF";
    
    DateTime result;
    result = DateTime.ParseExact(date, inFormat, CultureInfo.InvariantCulture);
    
    string reformat = (result.ToString(outFormat)); // => "26/11/2014 15:46:56.107"
}

So, you can create some strategy to make sure the fractional-second part of your string is a maximum of seven characters long; something like this:

string date = "2014-11-26 15:46:56.107123456789";

string secFrac = date.Substring(date.IndexOf('.') + 1);

if (secFrac != date) // there is a fractional seconds part
{
    if (secFrac.Length > 7)
    {

        date = date.Replace(secFrac, secFrac.Substring(0, 7));
    }
}

try to give like below

class Program
   {

       public static DateTime GetDateTimeFromString(String date)
       {
           return DateTime.ParseExact(date, "dd/MM/yyyy HH:mm:ss.fff", CultureInfo.InvariantCulture);
       }
       static void Main(string[] args)
       {
       DateTime S=   Program.GetDateTimeFromString("26/11/2014 15:46:56.107");
           Console.WriteLine(S);
           Console.ReadLine();

           // "26/11/2014 15:46:56.107000000"



       }
   }

Why aren't you using Convert.ToDateTime()

string str = "2014-11-26 15:46:56.107000000";
DateTime dt = Convert.ToDateTime(str);

This is simply working.