C#

public string RemoveSpecialCharacters(string str)
       {
           StringBuilder sb = new StringBuilder();
           for(int i=0; i<str.Length;i++)
           {
               if((str[i] >= '0' && str[i] <='9')
                   ||( str[i] >='A' &&  str[i]<='z'|| (str[i]=='-' || str[i] == '+' || str[i] == '*' || str[i] == '/' || str[i] == '%'|| str[i] ==')' || str[i] == '(')))
               {
                   sb.Append(str[i]);
               }
           }
           return sb.ToString();
       }
       private void button8_Click(object sender, EventArgs e)
       {
           string refine_string = RemoveSpecialCharacters(textBox1.Text);
           string[] split_var = refine_string.Split('+', '-', '/', '%', '^', '*', '=',')','(');
           double value;
           string str = "";
           for (int i = 0; i < split_var.Length; i++)
           {
               if (double.TryParse(split_var[i], out value))
               {
                   split_var[i] = " ";
               }
           }
           split_var = split_var.Where(s => s != " ").ToArray();
           string[] variables = split_var.Distinct().ToArray();

           for (int j = 0; j < variables.Length; j++)
           {

               str = str + variables[j] + '=' + ";";

           }
           textBox2.Text = str.TrimEnd(';');

       }

public class TblDepartments {

    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Iserial { get; set; }
    public nvarchar(50) Department { get; set; }
    public int ParentIserial{ get; set; }
    public IEnumerable<TblDepartments> items { get; set; }
}

I have the code below for scanning all papers. It works but the problem is when all papers will finish, it shows the error:

Exception User-Unhandeled System.runtime.InterpService.COMEException: Exception From HRESULT:0*80210003

which belongs to this line:
var imgFile = (ImageFile)ScanerItem.Transfer();
Does anyone know how to fix it?
Thanks

How can i fix it? Here is the code:

bool continueScanning2 = true;
    try
    {
        await Task.Run(() =>
        {
            var deviceManager = new DeviceManager();
            DeviceInfo AvailableScanner = null;
            while (continueScanning2)
            {
                for (int i = 1; i <= deviceManager.DeviceInfos.Count; i++)
                {
                    if (deviceManager.DeviceInfos[i].Type != WiaDeviceType.ScannerDeviceType) // Skip device If it is not a scanner
                    {
                        continue;
                    }
                    AvailableScanner = deviceManager.DeviceInfos[i];
                    break;
                }
                var device = AvailableScanner.Connect();
                var ScanerItem = device.Items[1];
                var imgFile = (ImageFile)ScanerItem.Transfer();
                var data = (byte[])imgFile.FileData.get_BinaryData();
                var bitmap = GetBitmapFromRawData(imgFile.Width, imgFile.Height, data);
                string name2 = Guid.NewGuid().ToString().Replace("-", "") + ".jpg";
                var Path = @"C:\Users\...\Desktop\test\" + name2; // save the image in some path with filename.
                pictureBox1.ImageLocation = Path;
                bitmap.Save(Path, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        });
    }
    catch (COMException ex)
    {
        MessageBox.Show(ex.Message);
    }