The install popup shows up if 6 or more Web TWAIN objects are opened on IE 10/11

Sometimes the users might try to access the scan page several times on IE 10/11. On the 6th try, the users will start getting a prompt that says Dynamic Web TWAIN isn’t installed and the scan page stops working.

Each Web TWAIN object establishes a WebSocket connection with the local service. However, IE 10/11 has a limit on the maximum number of concurrent WebSocket connections which is 6. Once the limitation is exceeded, the newly created Web TWAIN object will not be able to connect with the local service and thus deems it uninstalled.

1. Close the WebSocket proactively by calling the method Dynamsoft.WebTwainEnv.Unload();.

More details about the Dynamsoft.WebTwainEnv.Unload() method are available in this KB article.

2. Open the Local Group Policy Editor and configure the WebSocket object for IE. The following is the propositional steps.

    1). Press the Windows + R keys to open the Run dialog.
    2). Type gpedit.msc, and press Enter.
    3). To change the maximum number of concurrent WebSocket connections go to: Administrative Templates > Windows Components > Internet Explorer > Security Features > AJAX.
    4). Double click in the corresponding feature: Maximum number of connections per server, enable the feature and change the default number of connections to a larger number.
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