public List<int> LoadFileForNumberOfErrors() { var MyTextFileDataSet = new TextFileDataSet.TextFileDataSet(); using (var filestream = new FileStream("//Path to file", FileMode.Open, FileAccess.Read,FileShare.None)) { MyTextFileDataSet.ContentExpression = new Regex(@"^(?<date>[^ ]+) (?<time>[^A-Z]+) (?<errorMessage>[^[]+) \[1\] (?<programName>[^.]+)[.](?<formName>[^.]+)[.](?<event>[^ ]+)[^a-z]+(?<username>[^:]+):(?<message>[^.]+).+$", RegexOptions.Multiline); MyTextFileDataSet.Fill(filestream); filestream.Flush(); filestream.Dispose(); }