Maybe:

public static object GetDefault(Type t)
        {
            if (t.IsValueType)
            {
                return Activator.CreateInstance(t);
            }
            return null;
        }

then:

var passedObject = SafeConvert(passedValue, GetDefault(columnType));

>>Do you seem how can we replace Convert.ChangeType with SafeConvert in this code
>>
>>

>> foreach (KeyValuePair<String, String> kvp in rowValues)
>>         {
>>            String passedValue = kvp.Value;
>>            var columnValue = bookingRow[kvp.Key];
>>            Type columnType = ((DataColumn)bookingRow[kvp.Key]).DataType;
>>
>>            var passedObject = Convert.ChangeType(passedValue, columnType);
>>            if (passedObject.Equals(columnValue) == false)
>>            {
>>               String cColumnValue = columnValue.ToString().Trim();
>>               if (cColumnValue!=passedValue) // Double check to prevent cases of "" vs. "          "
>>                  this.SaveToBookingHistory(booking_id, "M", kvp.Key, cColumnValue, passedValue, ref messageText, ref statusCode);
>>            }
>>         }

>
>
>See my other answer