Symptoms:

You may find the session is lost when you try to upload files to your web server using Dynamic Web TWAIN.

Cause: 

1. You are using an old version of Dynamic Web TWAIN that does not support session.

2. You are using an authentication mode that the Dynamic Web TWAIN version you are using does not support.

3. The IP you typed in the address bar of browser is inconsistent with the one you specified in the HTTP Upload method.

4. You are using .NET Framework 2.0 and HttpOnly in the Global file is set to true.

5. You have some old cookies stored on your local machine.

Resolution: 

1. Please make sure you are using Dynamic Web TWAIN 5.1 or above which supports session. The latest version is recommended.

For information on how to upgrade, please click here.

2. Please check what's new page here to see if the version you are using supports the authentication mode you use.

3. Please make sure the IP you specified in the HTTP Upload method is consistent with the one you type in the address bar of IE.

4. If you use Form Authentication, please check out this article on how to use it.

5. If you are using .NET Framework 2.0, please make sure that HttpOnly in the Global file is set to false.

6. Please delete the browsing history of IE (Tools->Internet Options->General), close IE and try running the application again.

If the issue persists, you can use SetCookie method to set the current cookie into the HTTP Header.

Also, we provide session test samples. Click here for info on how to get them.