cefsharp/CefSharp · info · Exception

Expected Exception

Error message

Expected Exception

What it means

Thrown by AsyncBoundObject.AsyncThrowException() after a 2-second delay — example/test code that demonstrates how async C# methods propagate exceptions to JavaScript. Marked [DebuggerHidden] so Visual Studio does not break on it. Not a production error; it exists to exercise the async-exception bridge.

Source

Thrown at CefSharp.Example/JavascriptBinding/AsyncBoundObject.cs:257

        }

        public async Task<string[]> AsyncDownloadFileAndSplitOnNewLines(string url)
        {
            var webClient = new WebClient();
            var download = await webClient.DownloadStringTaskAsync(new Uri(url));

            var lines = download.Split('\n').Where(x => !string.IsNullOrEmpty(x.Trim())).ToArray();

            return lines;
        }

        //We expect an exception here, so tell VS to ignore
        [DebuggerHidden]
        public async Task<string> AsyncThrowException()
        {
            await Task.Delay(2000);

            throw new Exception("Expected Exception");
        }

        public uint UIntAddModel(UIntAddModel model)
        {
            return model.ParamA + model.ParamB;
        }

        public uint UIntAdd(uint paramA, uint paramB)
        {
            return paramA + paramB;
        }

        public async Task<string> JavascriptOptionalCallbackEvalPromise(bool invokeCallback, string msg, IJavascriptCallback callback)
        {
            using (callback)
            {
                if (invokeCallback)
                {

View on GitHub (pinned to 16bc6e0711)

Solutions

1. Expected in example code — not a real defect.
2. If copied into your app, remove the method or wrap your JS caller in try/catch.
3. For your own async bound methods, ensure exceptions are intentional and documented.

Example fix

// JavaScript
try { await asyncBoundObj.asyncThrowException(); }
catch (e) { console.log('Handled:', e.message); }

// In JavaScript
try { await asyncBoundObj.asyncThrowException(); }
catch (e) { console.log('Handled:', e.message); }

When it happens

Trigger: Calling the bound asyncThrowException method from JavaScript in the example browser. Only present in CefSharp.Example.

Common situations: Running the example app's test page. Not encountered unless you reference AsyncBoundObject.

Related errors

• This is an exception coming from C#
• Nested Exception Invalid
• Nested Exception Canceled
• IBrowser
• frame

AI-assisted analysis of cefsharp/CefSharp@16bc6e0711 (2026-08-13). Data as JSON: /api/errors/ebe04cdb8923c5a1. Report an issue: GitHub.