Unhandled "Cannot access a disposed object" exceptions occurs randomly

[DominikPalo]

I'm using CefSharp (v45.0.0) in WPF app (WPF Chromium control) and my app sometimes crashes with an exception "Cannot access a disposed object". It happens during creating (opening) a new WPF window with the Chromium control.

"Cannot access a disposed object.
Object name: 'CefSharp.Internals.BrowserProcessServiceHost'.    
at System.ServiceModel.Dispatcher.ChannelDispatcherCollection.InsertItem(Int32 index, ChannelDispatcherBase item)   
at System.Collections.Generic.SynchronizedCollection`1.Add(T item)   
at System.ServiceModel.Description.DispatcherBuilder.InitializeServiceHost(ServiceDescription description, ServiceHostBase serviceHost)   
at System.ServiceModel.ServiceHostBase.InitializeRuntime()   
at System.ServiceModel.ServiceHostBase.OnBeginOpen()   
at System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)   
at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)   
at CefSharp.ManagedCefBrowserAdapter.OnAfterBrowserCreated(Int32 browserId)   
at CefSharp.Internals.ClientAdapter.OnAfterCreated(ClientAdapter* , CefRefPtr<CefBrowser>* browser)"

[amaitland]

What other information can you provide? What does your code look like? Anything you might be doing slightly out of the ordinary? Ideally we need a way to reproduce the problem.

Do you use RegisterJsObject? If not you can disable the WCF service and get around the problem.

[DominikPalo]

Yes, I'm using RegisterJsObject in the constructor of containing window (and in 99% of attempts it works without any problem):

    public ChatWindow()
    {
        InitializeComponent();
        Owner = Application.Current.MainWindow;

        Messenger.Default.Register<NotificationMessage>(this, (message) =>
        {
            DispatcherHelper.CheckBeginInvokeOnUI(() =>
            {
                if (message.Notification == "CloseWindowsBoundToMe" 
                    && message.Sender == DataContext)
                {
                    Close();
                }
            });

        });

        browser?.RegisterJsObject("bound", (DataContext as ChatWindowViewModel).Bound);
    }

And XAML:

<Window x:Class="Client.Windows.ChatWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:cefSharp="clr-namespace:CefSharp.Wpf;assembly=CefSharp.Wpf"
        mc:Ignorable="d" DataContext="{Binding ChatWindow, Source={StaticResource Locator}}"
        ResizeMode="NoResize" WindowStartupLocation="CenterOwner"
        Icon="/slido;component/slido.ico" WindowStyle="ToolWindow"
        Title="LiveAgent" SizeToContent="WidthAndHeight">

    <cefSharp:ChromiumWebBrowser Width="350" Height="450" x:Name="browser" WebBrowser="{Binding WebBrowser, Mode=OneWayToSource}" 
Address="{Binding ChatUrl}" />

</Window>

[amaitland]

Does Close ever get called just after the Window has been opened?

[DominikPalo]

No, the Close event is called from inner JavaScript (using a Bound object) only after user clicks on "Close" HTML element/control displayed on web.

[amaitland]

Well somehow your disposing of the BrowserProcessServiceHost before it's open
https://github.com/cefsharp/CefSharp/blob/cefsharp/45/CefSharp.Core/ManagedCefBrowserAdapter.cpp#L61

https://github.com/cefsharp/CefSharp/blob/cefsharp/45/CefSharp.Core/ManagedCefBrowserAdapter.h#L103

[amaitland]

Added a simple try/catch around the Open call. Change will be in 47.0.0 release.

86b5c54

If you can reproduce with that change then this can be reopened. (Ideally investigate further and submit a PR with a proposed solution).