Troubleshooting

Installing the Virtual Scanner for testing

If you don't have an actual scanner available for testing, you can download and install a virtual scanner (a scanner simulator), which was developed by the TWAIN Working Group, to test the basic scanning features of Dynamic Web TWAIN. Download 32 bit virtual scanner Download 64 bit virtual scanner

Is my scanner driver TWAIN compliant

If you are not sure whether your scanner is TWAIN compliant, you can use TWACKER, a tool developed by the TWAIN Working Group, to verify it.

TWACKER can be downloaded here: TWACKER 32 bit   TWACKER 64 bit After installation:

  • Launch the program.
  • Click menu File->Select Source and select your device in the 'Select Source' list.
  • If your device is not listed, please check if the driver is installed. Or, you can try running TWACKER as "Admin" since you may not have permission to access the data source.
  • Click menu File->Acquire to do scanning.

If the scanning is successful without any errors, then your device should be TWAIN compliant.

If it fails, you may have to search online or contact the device vendor for a TWAIN driver.

Why is my scanner not shown or not responding in the browser

Please check out http://kb.dynamsoft.com/questions/541/

Why does Dynamic Web TWAIN fail to upload my documents

When you use forms authentication in your web application, you might fail to upload documents to the server using Dynamic Web TWAIN in IE 6~9. This happens because Dynamic Web TWAIN still works as an ActiveX in IE 6~9 and it performs the upload as an independent user-agent, one that might not have permission to get the authentication cookie during the upload.

The root cause of the issue is the missing cookie for the authentication. So the solution is to locate the cookie and bind it to the upload request. To do this, Dynamsoft has provided an API called SetCookie.

The following are the steps, we use ASP.NET (C#) in the example:

  1. Print the cookie out explicitly in the page and assign it to a JavaScript variable: var cookie = "<%=Request.Headers["Cookie"] %>";
  2. Set the cookie at runtime before you call any HTTP Upload method: DWObject.SetCookie(cookie);
    DWObject.HTTPUpload…

That's it.
NOTE:
The above solution is very straightforward but it exposes the authentication cookie which might be seen as a security breach. If this is not an acceptable solution, we also offer a workaround using AJAX. For more info, please contact us at live help: http://www.dynamsoft.com/Support/LiveHelp.aspx

More Troubleshooting Topics

For more troubleshooting topics, please check out: http://kb.dynamsoft.com/categories/Dynamic+Web+TWAIN/