Error Troubleshooting

Error Message - Uncaught TypeError: Cannot read properties of null (reading ‘appendChild’) or Failed to execute ‘appendChild’ on ‘Node’: parameter 1 is not of type ‘Node’.

Symptom:

You may see the following errors when you open your application. These errors may be sporadic or may halt your application.

• Uncaught TypeError: Cannot read properties of null (reading ‘appendChild’)

• Uncaught TypeError: Failed to execute ‘appendChild’ on ‘Node’: parameter 1 is not of type ‘Node’

Cause:

Typically, an application uses DWObject = Dynamsoft.DWT.GetWebTwain('dwtcontrolContainer') to create the object at the target container. There are certain conditions where Dynamic Web TWAIN’s initialization process will complete, but after initialization, the target container is not defined or remains null. You will then see the error when trying to upload your files.

Workaround:

Please check if your container is created dynamically (especially if you are using dynamic frameworks). There are two ways to address the issue.

(1) If you want to use dynamic initialization method, here is sample code to create the object dynamically:

Dynamsoft.DWT.CreateDWTObjectEx(
    {
        WebTwainId: 'myDWT'
    },
    function(obj) {
        DWObject = obj;
        DWObject.Viewer.bind(document.getElementById('dwtcontrolContainer'));
        DWObject.Viewer.height = 400;
        DWObject.Viewer.width = 600;
        DWObject.Viewer.show();
    },
    function(err) {
        console.log(err);
    }
);

(2) If you want to use default initialization method, please set Dynamsoft.DWT.AutoLoad to false and manually implement Dynamsoft.DWT.Load() after you confirm the container has been created.