AddHostObjectToScript - Caching chrome.webview.hostObjects.external in a variable causes Error: Element not found. (0x80070490)

[dorofino]

Hi,

I'm using the following code to call a method from Javascript

using System.Diagnostics;
using System.Runtime.InteropServices;

        private bool _hostObjectAdded = false;
        private void AddHostObject()
        {
			if (!_hostObjectAdded)
			{
				_hostObjectAdded = true;
				webView.CoreWebView2.AddHostObjectToScript("external", new BrowserHostObject());
			}
		}

        async void WebView_NavigationStarting(object sender, CoreWebView2NavigationStartingEventArgs e)
        {
            _isNavigating = true;
            RequeryCommands();

            await webView.EnsureCoreWebView2Async();
            AddHostObject();
        }

	[ClassInterface(ClassInterfaceType.AutoDual)]
	[ComVisible(true)]
	public class BrowserHostObject
	{ 
		public bool Test(string something)
		{
			string message = $"***Test({something}) Called***";
			Debug.Print(message);
			return true;
		}
	} 

The JavaScript method looks like this

 <button onclick="JsTest()">Test Call</button>
<script>
        const external = chrome.webview.hostObjects.external;
        function JsTest() {
                external.Test('This is a test');
        }
</script>

After a couple of clicks and randomly I get the following error.

Error: Element not found. (0x80070490)

It works again when I right-click on the page and reload the content on the WebView2, without restarting the program.
Does anyone know why this happens?

AB#28271329

[champnic]

I believe this is because you are caching the 'external' object in JS, and I think this has caused some garbage collection related issues in the past (or something similar). Can you try using the full path to call?
chrome.webview.hostObjects.external.Test('This is a test');

Let me know if that fixes it for you. I've opened a bug on our end to look into this. Thanks!

[dorofino]

It looks like it works!
You are a genius!

I believe this is because you are caching the 'external' object in JS, and I think this has caused some garbage collection related issues in the past (or something similar). Can you try using the full path to call?
chrome.webview.hostObjects.external.Test('This is a test');

Let me know if that fixes it for you. I've opened a bug on our end to look into this. Thanks!

[pontusn]

We also experience limited life-time for proxies. Sofar we have implemented workarounds by using full-path access. For entities in our model we cache IDs and use lookup functions. And in few situations where the COM object is only referred from JS we had to publish references to sn external collection implemented in C++.

[pagoe-msft]

Hi Everyone,

This was addressed in the 1.0.707-prerelease version.

[DexterWoo]

we recently saw a similar error in our project.
the same thing is we also created a js proxy object to hold the full-path injected object.
is that really fixed in the webview2 release after 1.0.707-prerelease? we are using 1.0.1293.44 now

[pontusn]

Regression problems may occure, but we did not experience any lifetime issues in our application since the fix was introduced.