Why is my C# WebBrowser Control Hanging on AJAX Calls, and How Can I Fix It?

Troubleshooting AJAX Issues in C#'s WebBrowser Control

The C# WebBrowser control sometimes struggles with AJAX calls, leading to a frustrating "Your request is being processed" hang. This behavior differs significantly from a full IE browser, which usually handles these calls without issue.

The solution often lies in configuring Feature Control to better align the WebBrowser control's behavior with that of a standard IE instance. Crucially, setting the "FEATURE_BROWSER_EMULATION" feature ensures improved script compatibility.

Here's a function to modify the registry settings:

<code class="language-csharp">private void SetBrowserFeatureControlKey(string feature, string appName, uint value)
{
    using (var key = Registry.CurrentUser.CreateSubKey(
        String.Concat(@"Software\Microsoft\Internet Explorer\Main\FeatureControl\", feature), 
        RegistryKeyPermissionCheck.ReadWriteSubTree))
    {
        key.SetValue(appName, (UInt32)value, RegistryValueKind.DWord);
    }
}</code>

This function is used within SetBrowserFeatureControl():

<code class="language-csharp">private void SetBrowserFeatureControl()
{
    // Avoid modifying settings in the Visual Studio debugger
    var fileName = System.IO.Path.GetFileName(Process.GetCurrentProcess().MainModule.FileName);
    if (String.Compare(fileName, "devenv.exe", true) == 0 || String.Compare(fileName, "XDesProc.exe", true) == 0) 
        return;

    // Register necessary features (see detailed explanation below for a comprehensive list)
    // ...
}</code>

To ensure these changes are applied before the WebBrowser control initializes, call SetBrowserFeatureControl() in your main form's constructor:

<code class="language-csharp">public MainWindow()
{
    SetBrowserFeatureControl();
    InitializeComponent();
    //...
}</code>

For a complete list of recommended Feature Control settings to resolve various compatibility problems, refer to this resource: Browser Feature Control Key Settings This will provide a more robust solution to AJAX-related hanging issues within the WebBrowser control.

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