ERROR: ActiveX control cannot be instantiated because the current thread is not in a single-threaded apartment.

Question

User1046245955 posted

anyone can help me regarding this error im using c# .net 

ActiveX control cannot be instantiated because the current thread is not in a single-threaded apartment.

here's my code for scanning a document with twain dll

string strMM = "";
string strDD = "";
int srlNo = 1;
string strfilename = "";
try
{
strfilename = DateTime.Now.ToString("ddMMyyyyhhmm") + "_" + "CF" + ".pdf";
{
//var withBlock = AxTwain2;

var withBlock = new AxTwain();

if (!withBlock.SelectDevice())
return;

if (!withBlock.HasADF)
{
ScriptManager.RegisterStartupScript(this, this.GetType(), "script", "alert('No Automatic Document Feeder(Scanner) detected on this Computer. Are you sure you want to continue?');", true);
return;
}
withBlock.UseADF = true;
withBlock.MultiImage = true;
withBlock.KeepImages = false;
withBlock.ImagesToRead = 0;
withBlock.UseInterface = false;
withBlock.PixelType = TxPixelType.ptRGB;
withBlock.ClearPDF();
withBlock.Acquire();
withBlock.WritePDF(strfilename);
System.Diagnostics.Process.Start(strfilename);
}
}
catch (Exception ex)
{
 Interaction.MsgBox(ex.Message);
}

Answer 1

User-893317190 posted

Hi paminchever,

The errors shows that your code should run in a single-threaded apartment.

Webform runs in a muti-thread environment by default.

To solve this,one way it to  set the AspCompat of page directive , another way is to start a new thread to run your code and set its environment to single-threaded.

For more information , please refer to

https://www.syncfusion.com/kb/6394/how-to-fix-the-threadstateexception-activex-control-cannot-be-instantiated-exception-when-converting

Best regards,

Ackerly Xu