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ErrorMode Property

Indicate how to handle errors when reading barcodes.
public BarcodeReaderErrorMode ErrorMode { get; set; } 
Public Property ErrorMode As BarcodeReaderErrorMode 
@property (nonatomic, assign) LTBarcodeReaderErrorMode errorMode 
public BarcodeReaderErrorMode getErrorMode() 
public void setErrorMode(BarcodeReaderErrorMode value) 
property BarcodeReaderErrorMode ErrorMode { 
   BarcodeReaderErrorMode get(); 
   void set (    BarcodeReaderErrorMode ); 

Property Value

An BarcodeReaderErrorMode enumeration member that indicates how to handle errors when reading barcodes. The default value is BarcodeReaderErrorMode.Default.


The BarcodeReader object might encounter errors when reading barcodes. By default, when an error is encountered, an exception is thrown, usually of type BarcodeException with the BarcodeException.Code set to one of the BarcodeExceptionCode enumeration members for more details regarding the error. This is the default behavior.

Sometimes, this behavior is not the desired one, for example:

  • The application is trying to decode barcodes on an "if found and correct" basis. If there were corrupted barcodes, the action is to ignore them and to continue. In this case, you can set the error mode to BarcodeReaderErrorMode.IgnoreAll.

    The application is reading multiple barcodes from an image, and the action is to ignore the corrupted barcodes and return only the valid ones found. In this case, you can set the error mode to BarcodeReaderErrorMode.IgnoreAll and subscribe to the BarcodeReader.ReadSymbology event to get a notification when an error occurs and save the exception for later use. You can then handle these errors when all barcodes are read and the read method returns.

The LEADTOOLS C# and VB Barcode Demo changes the value of ErrorMode to BarcodeReaderErrorMode.IgnoreAll and uses the BarcodeReader.ReadSymbology event to show the errors encountered in a list box.

Note that when the BarcodeReader does not find any barcodes in the image, no exception is thrown. Instead, BarcodeReader.ReadBarcode and BarcodeReader.ReadBarcodes methods will return null (Nothing in VB) or an empty array of BarcodeData type.


This example changes the value of BarcodeReader.ErrorMode before reading all the barcodes from an image. It will then show any errors encountered after the read operation returns.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Barcode; 
using Leadtools.ImageProcessing; 
		private List<Exception> myErrors;   // List of errors 
				public void BarcodeReader_ErrorModeExample() 
			string imageFileName = Path.Combine(LEAD_VARS.ImagesDir, "Barcode1.tif"); 
			// Create a Barcode engine 
			BarcodeEngine engine = new BarcodeEngine(); 
			// Get the Barcode reader instance 
			BarcodeReader reader = engine.Reader; 
			// Load the image 
			using (RasterCodecs codecs = new RasterCodecs()) 
				using (RasterImage image = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1)) 
					myErrors = new List<Exception>(); 
					// Disable the errors 
					reader.ErrorMode = BarcodeReaderErrorMode.IgnoreAll; 
					// Subscribe to the ReadSymbology event 
					reader.ReadSymbology += new EventHandler<BarcodeReadSymbologyEventArgs>(myReader_ReadSymbology); 
					// Read all barcodes in the image 
					reader.ReadBarcodes(image, LeadRect.Empty, 0, null); 
					reader.ReadSymbology -= new EventHandler<BarcodeReadSymbologyEventArgs>(myReader_ReadSymbology); 
					// Show the errors 
					if (myErrors.Count > 0) 
						Console.WriteLine("Errors encountered:"); 
						foreach (Exception error in myErrors) 
		private void myReader_ReadSymbology(object sender, BarcodeReadSymbologyEventArgs e) 
			// If we encounter an error, save it to our list 
			if (e.Error != null) 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Barcode 
Imports Leadtools.ImageProcessing 
Private myErrors As List(Of Exception)  ' List of errors 
Public Sub BarcodeReader_ErrorModeExample() 
   Dim imageFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Barcode1.tif") 
   ' Create a Barcode engine 
   Dim engine As New BarcodeEngine() 
   ' Get the Barcode reader instance 
   Dim reader As BarcodeReader = engine.Reader 
   ' Load the image 
   Using codecs As New RasterCodecs() 
      Using image As RasterImage = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1) 
         myErrors = New List(Of Exception)() 
         ' Disable the errors 
         reader.ErrorMode = BarcodeReaderErrorMode.IgnoreAll 
         ' Subscribe to the ReadSymbology event 
         AddHandler reader.ReadSymbology, AddressOf myReader_ReadSymbology 
         ' Read all barcodes in the image 
         reader.ReadBarcodes(image, LeadRect.Empty, 0, Nothing) 
         RemoveHandler reader.ReadSymbology, AddressOf myReader_ReadSymbology 
         ' Show the errors 
         If myErrors.Count > 0 Then 
            Console.WriteLine("Errors encountered:") 
            For Each err As Exception In myErrors 
         End If 
      End Using 
   End Using 
End Sub 
Private Sub myReader_ReadSymbology(ByVal sender As Object, ByVal e As BarcodeReadSymbologyEventArgs) 
   ' If we encounter an error, save it to our list 
   If Not IsNothing(e.Error) Then 
   End If 
End Sub 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class 

Target Platforms

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Leadtools.Barcode Assembly