YouTube YTPlayer API and Webview2

[mikemeinz]

On November 1, 2025, my YouTube video player (Windows Forms, .NET, WebView2) program started displaying YouTube error 153. YouTube announced a change in July but it did not affect my program until November 1.

To solve YouTube YTPLAYER API Error 153, I did the following:

1. Added in the area of the HTML/Javascript string I passed into webView.NavigateToString():
   <meta name="referrer" content="strict-origin-when-cross-origin">

2. In my program, I added:

    WebView.CoreWebView2.WebResourceRequested += webResourceRequestedHandler;
    
    private void WebResourceRequestedHandler(object sender, CoreWebView2WebResourceRequestedEventArgs e) 
    { 
        try 
        { 
            var headers = e.Request.Headers; 
            headers.SetHeader("Referer", "https://MYWEBSERVERHOSTNAME"); 
        } 
        catch (Exception ex) 
        { 
            MessageBox.Show("Exception: Setting header: " + ex.Message); 
        } 
    } 

[mikemeinz]

Documented how to solve YouTube YTPLAYER API Error 153 when YTPLAYER API is used with WebView2.