[Problem/Bug]: FrameCreated event sometimes doesn't fire for nested iframes

[pushkin-]

What happened?

I'm seeing this issue in my app maybe 40-50% of the time, but in the WebView2 sample, I see it 100% of the time.

This might be specific to this website, but I'm seeing cases where FrameCreated isn't firing for a nested iframe.

For my general usecase, I haven't seen this problem, but since I don't know if this could start happening for the page I load in iframes, I'm marking this as Important out of caution. If we determine that this happens because of this specific site, then we can mark this Low.

Importance

Important. My app's user experience is significantly compromised.

Runtime Channel

Prerelease (Edge Canary/Dev/Beta)

Runtime Version

135.0.3146.0 canary

SDK Version

1.0.3116 pre-release

Framework

Winforms

Operating System

Windows 11

OS Version

24H2 OS Build 26100.2894

Repro steps

Setup:

1. open the WebView2 Sample WinForms app
2. In BrowserForm.cs, replace the body of WebView_HandleIFrames with:

var frame = args.Frame;
if (frame.Name == "myFrame")
{
    var breakHere = true;
}
frame.FrameCreated += WebView_HandleIFrames;

3. Set a breakpoint on the breakHere variable

Repro steps:

1. start the app and navigate to https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_iframe
2. Replace the iframe in that page with: <iframe src="https://example.com" name="myFrame"></iframe>
3. Notice that the breakpoint doesn't get hit

Alternatively, if you open devtools on that page and run this code: const a = document.createElement("iframe"); a.name = "myFrame"; a.src = "https://example.com"; document.body.appendChild(a);, then the breakpoint will get hit.

Like I said above, in my app, I see this roughly half the time, but can repro every time in the webview2 sample app. Maybe some kind of race condition?
Notably, this page creates a ton of iframes. Maybe this doesn't repro with a simpler page.

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response

[sivMSFT]

Hi @pushkin-,

Could you try using the alternative:

Consider using the NestedFrameCreated event handler in CoreWebView2. This event will fire for all nested frame created events on CoreWebView2. You can subscribe to the CoreWebView2::NestedFrameCreated event to track all nested frames.

Example:

webView2.CoreWebView2.add_NestedFrameCreated(
    new EventHandler<CoreWebView2FrameCreatedEventArgs>((sender, args) =>
    {
        var frame = args.Frame;
        if (frame.Name == "myFrame")
        {
            var breakHere = true;
        }
    })); 

Please let us know, if this works for you.

[pushkin-]

What is NestedFrameCreated? Are you talking about the FrameCreated event that I can subscribe to on the Frame object? This is exactly what I'm doing in my example. @sivMSFT

[krbharadwaj]

@pushkin- I used exact same steps, and for me it is hitting the breakpoint, which means I see that it is sending Frame created for myFrame as well...
Used below code for the replacement of WebView_HandleIFrames method..
var frame = args.Frame;
if (frame.Name == "myFrame")
{
var breakHere = true;
}

I have used winforms app only... COuld yop please provide more details if there is any other change you have made to the app?

[pushkin-]

WebView2WindowsFormsBrowser_FrameCreatedIssue.zip

huh - I don't believe I modified anything else. I uploaded the exact sample app I used above to repro this issue. Other people on my team are also able to repro. Maybe give that one a shot. @krbharadwaj

[krbharadwaj]

@pushkin- Apologies for missing out on the details...

I tried adding the iframe not replacing earlier...
But for replacing an existing iframe, I am also not getting the framecreated event...

Looking at the details of the issue it seems, your concerns is that for inner frames creation we are not getting framecreated event... to check that, I tried adding below html:
<iframe name="myframe" width="500" height="400" style="border:2px solid blue;" srcdoc=' <html> <head> <title>Inner Frame</title> </head> <body> <h3>Inner iFrame (myinnerframe)</h3> <iframe name="myinnerframe" src="https://www.example.com" width="300" height="200" style="border:2px solid red;"></iframe> </body> </html>'> </iframe>

With below app code :
` void WebView_HandleIFrames(object sender, CoreWebView2FrameCreatedEventArgs args)
{
var frame = args.Frame;
if (frame.Name == "myframe")
{
var breakHere = true;
}
frame.FrameCreated += WebView_HandleInnerIFrames;
}

    void WebView_HandleInnerIFrames(object sender, CoreWebView2FrameCreatedEventArgs args)
    {
        var frame = args.Frame;
        if (frame.Name == "myinnerframe")
        {
            var breakHere = true;
        }
    }`

And with this, breakpoint is hitting both of the breakHere statements...