[Problem/Bug]: On some windows user accounts, setting parent of webview in some contexts results in - Exception: System.InvalidOperationException: CoreWebView2 members cannot be accessed after the WebView2 control is disposed. ---> System.Runtime.InteropServices.COMException: The group or resource is not in the correct state to perform the requested operation. (Exception from HRESULT: 0x8007139F)

[benhbell]

What happened?

Hello. We have a Windows PPT Plugin that our customers use. We use the latest Webview2SDK. A subset of our users are encountering an issue where some of our webviews are not displaying.

They all have a consistent error that does not seem to match what we can see in the code. Only one of our dev computers and only one user account can replicate it.

The issue can be replicated on the same machine, with the same software as another working user account and we have tried many non-code things to resolve it.

Users that encounter this issue, will always encounter this issue with one specific webview use-case, which happens to be the most critical one. We are not using a framework or UI for this, it is a frameless window. Our other usecases that do require some UI uses WFP (but those generally work).

We have customers that have reported this on windows 8, 10, and 11 (both pro and home editions)

I will be attaching some resources for you to review for both a working user account and a non-working user account on a developer machine with mock content. Both users are administrators on the machine, and the user account with the issue was actually the first user created on the machine.

• logs from the debug console when walking through the user experience
• trace logs using the windows process trace (According to your troubleshooting guide)
• Screenshots of the webview utilities analizer for both users

Troubleshooting we have attempted

• Restarting the machine
• We have tried removing our plugin, deleting folders, and then re-installing
• Removing office 2016 and re-installing it (and deleting related folders)
• using add/remove program to reinstall webview2
• downloading webview2 manually and re-installing
• checking that the monitor, resolution, and zoom settings are the same for both user accounts
• Attempting to clear DPI settings or monitor cache settings in the registry (But unsure if this ever worked)

The code

Our project is large but in general, these are some parts of the code that are being used to both instantiate webview2 and then attempt to adjust the parent for some webview2 controllers.

We initialize webview2 - we use webview2 in more places than this, but we load up webviews for each slide and attempt to preload the content so that switching slides is seemless.

private async void InitializeWebView2()
        {
            CoreWebView2EnvironmentOptions options = new CoreWebView2EnvironmentOptions();
            Util.SetProxyServer(options);

            string dataPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData, Environment.SpecialFolderOption.Create), "folder");
            webView2Environment = await CoreWebView2Environment.CreateAsync(null, dataPath, options).ConfigureAwait(true);

            independentController = await webView2Environment.CreateCoreWebView2ControllerAsync(pptHWND).ConfigureAwait(true);

            controllersByURL = new Dictionary<string, CoreWebView2Controller>();
            controllerQueue = new Queue<CoreWebView2Controller>();

            for (int i = 0; i < CONTROLLER_COUNT; i++)
            {
                CoreWebView2Controller controller = await webView2Environment.CreateCoreWebView2ControllerAsync(pptHWND).ConfigureAwait(true);

                controller.CoreWebView2.Settings.UserAgent = Util.GenerateWebView2UserAgent();
                controller.CoreWebView2.Settings.AreDevToolsEnabled = Util.DevToolsEnabled();
                
                string listeners = Properties.Resources.VizEventListeners;
                await controller.CoreWebView2.AddScriptToExecuteOnDocumentCreatedAsync(listeners).ConfigureAwait(true);
                controller.CoreWebView2.WebMessageReceived += HandleWebMessageReceivedEvent;

                controller.CoreWebView2.NavigationCompleted += NavDone;
                controllerQueue.Enqueue(controller);
            }
        }

When a user presents a slide we call this, and start to set the parent of our webviews to the presenter window

 public void BeginSlideShow(int slideshowHWND, List<PESlide> slides, Func<bool> checkEOS)
        {
            foreach (CoreWebView2Controller controller in controllerQueue)
            {
                controller.ParentWindow = new IntPtr((int)slideshowHWND); //the debugger stops here the first time we get there, and throws an exception
            }
            UpdateAllSlides(slides);
        }

We get a stacktrace error

Exception: System.InvalidOperationException: CoreWebView2 members cannot be accessed after the WebView2 control is disposed. ---> System.Runtime.InteropServices.COMException: The group or resource is not in the correct state to perform the requested operation. (Exception from HRESULT: 0x8007139F)

Importance

Blocking. My app's basic functions are not working due to this issue.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

119.0.2151.72

SDK Version

stable

Framework

Other

Operating System

Windows 10, Windows 11, Other

OS Version

Microsoft Windows 11 Pro (10.0.22621.0))

Repro steps

Describing the Behavior

A working scenario results in the plugin working:

1. We can open all UIs that depend on webviews and have them displayed properly. A
2. If we look at task manager, we can see we many webview processes correctly loading a web page
3. We see network traffic using fidler
4. We do not see this webview exception in the logs.

A non-working scenario results in the plugin working in some cases where webviews are used

1. We can open all but one UI that depends on webviews. When we encounter the error, the webview never even displays to the user. We can still use other webviews before and after through other UI
2. If we look at task manager, we see webview processes that never load a page about:blank
3. We see no network traffic or requests leaving PPT
4. We see the webview exception in the logs.

Both accounts "SAY" according to the logs that they have the same DPI, zoom level, etc.

Repros in Edge Browser

Not Applicable

Regression

No, this never worked

Last working version (if regression)

No response

Attachments

• working-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-18-23.zip
• working-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-17-54.zip
• working-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-17-16.zip
• notworking-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-13-42.zip
• notworking-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-13-24.zip
• notworking-powerpnt.exe.WebView2Utilities.Report.2023-11-30-10-13-01.zip
• notworking-os-console-logs.txt
• working-os-consolelogs1.txt
• Traces:

[LiangTheDev]

WebView2 controller will be auto closed if the parent hwnd is destroyed. Is it possible that when switching slides, the old parent hwnd got destroyed before we reparent to the new hwnd? If that is the case, you might have to ensure that we reparent to a valid hwnd before the old one is destroyed.

[benhbell]

At face value this seems unlikely for two reasons

1. comparing console logs for both working and non-working user sessions, we logged out the controllers in both cases, they both seem to be "ready" and exist before we attempt to set the parent. Is there a more direct or trustworthy way for us to check if the controller has been destroyed other than logging it before we try to set the parent?

2. when we call BeginSlideShow after a user clicks on reader view in PPT, everything works fine and we never get the exception. When a user account encounters this, it is consistently throws the error when the user attempts to "Present" regardless of computer state.

3. This works for a % of our users with the same setup as the % of users that consistently encounter this issue. It would be strange to me that we are destroying the parent before starting the slideshow, but only on some users accounts on the same machine.

[LiangTheDev]

WebView could be closed if its browser process crashes which has events, Close is called, or parent hwnd is destroyed. There is no events to inform that WebView is closed, not sure whether you could get event when parent hwnd is destroyed.
If you take an ETW trace of the repro, then we should be able to figure out what is going on.
If it were due to parent hwnd being destroyed, it could be a race condition for when the hwnd is destroyed and then the indeterministic repro.

[benhbell]

Ok. I see this documentation around ensuring we listen to and handle some events. but this does not explain why it is occurring for some users and not others, always.

The user behavior that replicates this is:

• open powerpoint
• present

Creating a separate user on the same machine, and following the same steps, will never replicate the issue.

I cannot see why we would be closing or destroying the webview parent or process before, so the crashing might still be a possibility, but not the root cause. Why would the same code and software crash consistently for one user, and one browser window, but not the others if the behavior, machine, OS, software version and compatibility the same.

I have included two ETW traces as attachments (in one zip), we were not able to discern if there was a race condition. To me, a race condition means that sometimes, it should not repo, but with the repo user, it always repos. What kind of user settings might affect or influence a race condition if the user behavior is the same?

Additionally, is there a way to get a more clear error to know when we should be attempting to recreate the controller? or should we be checking for close events after any unexpected error.

[LiangTheDev]

Got it.
For browser process failure, there is CoreWebView2.ProcessFailed event.

Looking at the trace, the events in not-working-trace.etl showed that WebView browser process for powerpnt.exe was still running and Microsoft.MSEdgeWebView\WebView2_APICalled events indicates that ParentWindow were successfully updated 4 times. Nothing obnormal. For the closed WebView we reject the call and don't log WebView2_APICalled event. So, if we encountered exception when setting ParentWindow, it should be that the webview is closed. However, the trace is not taken from the begin, there is not enough info to figure out why webviews were closed.

[benhbell]

I can generate a new trace. I will restart the machine, start the trace before I open any other program, and then re-attach it.

…

On Thu, Nov 30, 2023 at 7:42 PM Liang Zhao - MSFT ***@***.***> wrote: Got it. For browser process failure, there is CoreWebView2.ProcessFailed event. Looking at the trace, the events in not-working-trace.etl showed that WebView browser process for powerpnt.exe was still running and Microsoft.MSEdgeWebView\WebView2_APICalled events indicates that ParentWindow were successfully updated 4 times. Nothing obnormal. For the closed WebView we reject the call and don't log WebView2_APICalled event. So, if we encountered exception when setting ParentWindow, it should be that the webview is closed. However, the trace is not taken from the begin, there is not enough info to figure out why webviews were closed. — Reply to this email directly, view it on GitHub <#4206 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAHL75E77Y4MIVLA3LVIDQDYHERY5AVCNFSM6AAAAABABSNJUWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQMZVGE2TANZQGQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[benhbell]

Hi team, Please find another version of the trace logs.

Steps I followed

• Restarted the machine
• Started the trace
• Launched visual studio code and ran the debugger
• Opened the presentation
• Clicked the present button
• Advanced the slide and replicated the issue
• After getting to the end of the PPT, exited then went back to beginning
• Clicked reader mode, which loads a webview fine.
• toggled through the slide.

Can I get an email to use to send you the updated trace?

[LiangTheDev]

You can contact me at lzhao@microsoft.com.

[benhbell]

From our email convo

The trace indicates that Controller::Close is called at time stamp 75.883671333. If we then try to set parent hwnd on this closed controller, it will throw exception.

Is it possible to find Close() call in the code and add logging/breakpoint to figure out what’s going on?

I reviewed the code and cannot find anywhere where we call a close event

 private async void DpiMonitorSetup(IntPtr pptHWND)
        {
            string dataPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData, Environment.SpecialFolderOption.Create), "pollev_dpi");
            CoreWebView2Environment dpiMonitorEnvironment = await CoreWebView2Environment.CreateAsync(null, dataPath).ConfigureAwait(true);
            dpiMonitor = await dpiMonitorEnvironment.CreateCoreWebView2ControllerAsync(pptHWND).ConfigureAwait(true);
            dpiMonitor.ShouldDetectMonitorScaleChanges = true;
            dpiMonitor.BoundsMode = CoreWebView2BoundsMode.UseRasterizationScale;
            dpiMonitor.RasterizationScaleChanged += HandleRasterizationScaleChanged;
        }

Which is called from

 public void Startup(Microsoft.Office.Interop.PowerPoint.Application app)
        {
            string perfId = Guid.NewGuid().ToString();
            Util.PerfMarkToggle(true, "Startup powerpoint-" + perfId);
            try
            {
                MainThreadDispatcher = Dispatcher.CurrentDispatcher;
                //startup ppt code

                IntPtr pptWindowHandle = (IntPtr)app?.HWND;

                VizEmbedManager = new WebView2VizEmbedManager(pptWindowHandle);
                VizEmbedManager.HandleWebMessageReceivedEvent += HandleVizEmbedMessages;
                VizEmbedManager.HandleVizLogin += HandleVizEmbedLogin;

                WebAppModal = new WebView2WebAppModal(pptWindowHandle);
                WebAppModal.HandleWebMessageReceivedEvent += HandleWebAppModalMessages;

                DpiMonitorSetup(pptWindowHandle);

            }
            //catch (Exception ex)
        }

[champnic]

@benhbell Can you also do a search for "Close"? For any of the results in your screenshot where the CoreWebView2Controller is a variable, it could be "variable.Close()" instead of "CoreWebView2Controller". (If you already did this, please disregard this comment)

[sf-mzh]

Hi,

I'm focusing the same problem, however I can see that we doing something wrong. What I would like to know: Why does it work for more than 99% of our customer and a very small number of users gets into this failure.

So what we do is:

_hiddenHwndSource = new HwndSource(new HwndSourceParameters("Hidden", 1, 1) { WindowStyle = 0x02C00000 });
_hiddenHwndSource.RootVisual = _webView2Core;

and later on we switch it in to our view with the following code:

_hiddenHwndSource.RootVisual = new FrameworkElement(); // to unlink the webView2 Control from the hidden Source (I guess due to compatibility with older .NET Frameworks)
_hiddenHwndSource.Dispose(); // I guess this is the codeline which disposes the webview2Core (for a very small amount of users)
_webView2PresentationPanel.Children.Add(_webView2Core); // here it throws the exception

My problem is: I want to know how reproduce the problem, so I can relably say moving the Dispose one line down solves the problem. So under what conditions does Disposing the HwndTarget directly disposes the webview2Core?
@benhbell: Does the one developer system has touch or pen input enabled?

-Markus