Help! The app crashes when it starts. #8933

Daoting · 2022-05-31T03:45:08Z

Daoting
May 31, 2022

This bug has puzzled me for a long time. I spent more than ten days and couldn't find the cause of the problem. I tried everything I could think of but failed. This bug only has to do with the ui of the first page. If the first page contains only system controls, it will always work correctly. This bug exists on both Android and iOS.
Now I'll describe the most likely cause:

To reproduce the bug, I created an empty project and added the original files to the project one by one, and the app worked fine. When a certain number of files are added, the application suddenly starts crashing, but not particularly frequently. As the number of files increases, crashes become more frequent.

The output is different every time on android, but each time the following is included:
[monodroid-assembly] open_from_bundles: failed to load assembly System.Linq.Expressions.dll

The full output on Android
android.txt

The full output on iOS
ios1.txt
ios-nodebug.txt

It seems to be a deadlock caused by multithreading. This can be caused when loading the style of custom controls.

I upload the project for debugging.
Crash.zip
Normal.zip

Please delete the include of the following file to avoid build errors:

C:\Users\xxx\.nuget\packages\xamarin.kotlin.stdlib\1.6.20.1\buildTransitive\net6.0-android31.0\Xamarin.Kotlin.StdLib.targets
C:\Users\xxx\.nuget\packages\xamarin.jetbrains.annotations\23.0.0.3\buildTransitive\net6.0-android31.0\Xamarin.Jetbrains.Annotations.targets

Thank you.

Answered by Daoting

Jun 6, 2022

I need a multi-layer UI interface, so the root element is Grid.
MainWin.Content = RootGrid;
And th frame is added dynamically after window activation. This may be the problem.

On android, just add a line of new Frame().Navigate(typeof(Page)); at the beginning and everything works fine. Even if the frame is not placed in the visual tree. I used this method to temporarily fix the bug on android.

#if WIN
            MainWin = new Window { Title = Stub.Inst.Title };
            MainWin.Activate();
#else
            MainWin = Window.Current;
#endif

#if ANDROID
            new Frame().Navigate(typeof(Page));
#endif

            RootGrid = new Grid();

            _dlgCanvas = new Canvas();
   …

View full answer

jeromelaban · 2022-05-31T12:06:57Z

jeromelaban
May 31, 2022
Maintainer

Thanks for the report. Could you also upload the logs for the android and iOS devices? There may be some logging that could be useful. It also looks like there's no Uno logging available in your logs, you'll likely need to validate that the loggers configuration is appropriate (in app.xaml.cs, if you use the default template).

3 replies

Daoting Jun 1, 2022
Author

I have used the default loggers configuration. I've never understood why there is no log output when crashing, but there is log output when it works properly.

Normal

Normal.mp4

Crash

Crash.mp4

There is no regularity in crashing, sometimes it stops debugging automatically, and sometimes it gets stuck.
To find bugs, I even reinstalled windows and the development environment, troubleshooting each my custom control.

jeromelaban Jun 1, 2022
Maintainer

I'm not able to build your app :

1>Caused by: com.android.tools.r8.internal.f: Type org.jetbrains.annotations.Range is defined multiple times: C:\Users\jerome.laban\.nuget\packages\xamarin.jetbrains.annotations\23.0.0.3\buildTransitive\net6.0-android31.0\..\..\jar\org.jetbrains.annotations-23.0.0.jar:org/jetbrains/annotations/Range.class, obj\Debug\net6.0-android\lp\185\jl\libs\DB43F1C10974DC83.jar:org/jetbrains/annotations/Range.class

This is likely an issue caused by some net6-android tooling we have no control over.

Now, if you suspect a threading issue, when the app freeze (does not look like a crash because the app stays runnin), try pausing the debugger and take a look at the stacks from all threads. That may give some hints.

Daoting Jun 2, 2022
Author

This error is caused by referencing Square.OkHttp3 nuget packets. Because jar package duplication creates a conflict. Please delete the include of the following file to avoid build errors:

C:\Users\xxx\.nuget\packages\xamarin.kotlin.stdlib\1.6.20.1\buildTransitive\net6.0-android31.0\Xamarin.Kotlin.StdLib.targets
C:\Users\xxx\.nuget\packages\xamarin.jetbrains.annotations\23.0.0.3\buildTransitive\net6.0-android31.0\Xamarin.Jetbrains.Annotations.targets

I also try to see the stack of all threads. Thanks.

Daoting · 2022-06-06T07:35:05Z

Daoting
Jun 6, 2022
Author

I need a multi-layer UI interface, so the root element is Grid.
MainWin.Content = RootGrid;
And th frame is added dynamically after window activation. This may be the problem.

On android, just add a line of new Frame().Navigate(typeof(Page)); at the beginning and everything works fine. Even if the frame is not placed in the visual tree. I used this method to temporarily fix the bug on android.

#if WIN
            MainWin = new Window { Title = Stub.Inst.Title };
            MainWin.Activate();
#else
            MainWin = Window.Current;
#endif

#if ANDROID
            new Frame().Navigate(typeof(Page));
#endif

            RootGrid = new Grid();

            _dlgCanvas = new Canvas();
            RootGrid.AddHandler(UIElement.PointerPressedEvent, _pressedHandler, true);
            RootGrid.Children.Add(_dlgCanvas);

            NotifyPanel = new StackPanel { Spacing = 10 };
            RootGrid.Children.Add(NotifyPanel);

            MainWin.Content = RootGrid;
            MainWin.Activate();

But there are always different errors on ios, such as:

=================================================================
	Managed Stacktrace:
=================================================================
	  at <unknown> <0xffffffff>
	  at <>c__DisplayClass2_0:<.ctor>b__0 <0x00052>
	  at Microsoft.UI.Xaml.ResourceDictionary:TryMaterializeLazy <0x0008e>
	  at Microsoft.UI.Xaml.ResourceDictionary:GetThemeDictionary <0x000b6>
	  at Microsoft.UI.Xaml.ResourceDictionary:GetActiveThemeDictionary <0x00052>
	  at Microsoft.UI.Xaml.ResourceDictionary:GetFromTheme <0x0001a>
	  at Microsoft.UI.Xaml.ResourceDictionary:GetFromMerged <0x0017a>
	  at Microsoft.UI.Xaml.DependencyObjectStore:GetImplicitStyle <0x00150>
	  at Microsoft.UI.Xaml.DependencyObjectExtensions:StoreGetImplicitStyle <0x00026>
	  at Microsoft.UI.Xaml.FrameworkElement:ResolveImplicitStyle <0x00032>
	  at Microsoft.UI.Xaml.FrameworkElement:UpdateActiveStyle <0x0004a>
	  at Microsoft.UI.Xaml.FrameworkElement:ApplyStyle <0x00020>
	  at Microsoft.UI.Xaml.FrameworkElement:ApplyStyles <0x00010>
	  at Microsoft.UI.Xaml.FrameworkElement:OnLoadingPartial <0x00020>
	  at Microsoft.UI.Xaml.FrameworkElement:OnLoading <0x00010>
	  at Microsoft.UI.Xaml.FrameworkElement:MovedToWindow <0x0012e>
	  at System.Object:runtime_invoke_direct_void__this__ <0x0005a>
	  at <unknown> <0x00000>
	  at <unknown> <0xffffffff>
	  at ObjCRuntime.Messaging:void_objc_msgSendSuper <0x00076>
	  at UIKit.UIWindow:MakeKeyAndVisible <0x000ac>
	  at Microsoft.UI.Xaml.Window:InternalActivate <0x0003c>
	  at Microsoft.UI.Xaml.Window:Activate <0x00010>
	  at Dt.Core.SysVisual:.cctor <0x0028e>
	  at System.Object:runtime_invoke_direct_void <0x00054>
	  at <unknown> <0x00000>
	  at <unknown> <0xffffffff>
	  at <Init>d__27:MoveNext <0x002a6>
	  at System.Runtime.CompilerServices.AsyncMethodBuilderCore:Start <0x0005e>
	  at System.Runtime.CompilerServices.AsyncTaskMethodBuilder:Start <0x00010>
	  at Dt.Core.Kit:Init <0x0005e>
	  at <Launch>d__39:MoveNext <0x0018a>
	  at System.Runtime.CompilerServices.AsyncMethodBuilderCore:Start <0x0005e>
	  at System.Runtime.CompilerServices.AsyncTaskMethodBuilder:Start 
<0x00010>
	  at Dt.Base.DefaultStub:Launch <0x00088>
	  at Dt.Base.DefaultStub:OnLaunched <0x00028>
	  at Dt.Sample.App:OnLaunched <0x00024>
	  at Microsoft.UI.Xaml.Application:FinishedLaunching <0x00248>
	  at Dt.Sample.App:FinishedLaunching <0x00048>
	  at <Module>:runtime_invoke_direct_bool__this___UIApplication_NSDictionary <0x00058>
	  at <unknown> <0x00000>
	  at <unknown> <0xffffffff>
	  at UIKit.UIApplication:UIApplicationMain <0x0011e>
	  at UIKit.UIApplication:Main <0x0010e>
	  at Dt.Sample.EntryPoint:Main <0x00028>
	  at <Module>:runtime_invoke_direct_void_string[] <0x0004a>
	  at <unknown> <0x00000>
=================================================================

It took me a few more days and still couldn't fix it. The app crashes as soon as it starts and I can't continue working now.
@jeromelaban Please help me, thank you very much!

5 replies

jeromelaban Jun 6, 2022
Maintainer

I see that you're using this line:

<UseInterpreter Condition="'$(Configuration)' == 'Debug'">True</UseInterpreter>

This is currently broken in .NET: dotnet/runtime#68808

We're doing this in Uno:

uno/src/SolutionTemplate/UnoSolutionTemplate.WinUI.net6/Mobile/UnoQuickStart.Mobile.csproj

Lines 16 to 18 in 7fe39e5

    
           <!-- Disabled because of https://github.com/dotnet/runtime/issues/68808 --> 
        
           <!--<UseInterpreter Condition="'$(Configuration)' == 'Debug' and '$(TargetFramework)' != 'net6.0-maccatalyst'">True</UseInterpreter>-->

Daoting Jun 7, 2022
Author

There are still bugs. It seems that something didn't end initialization when I first started the homepage.

I can't just add one line of code like on android. My current approach is to write a page that contains only one button as the home page, and then manually navigate to the original home page, which is always normal. However, it cannot be used by users.😊

The following are common bugs on ios.
bug1.txt
bug2.txt

This may not be a bug for uno. But I can only turn to you for help.
Thanks.

jeromelaban Jun 7, 2022
Maintainer

This looks like a native crash and we won't be able to help there, only the .NET team will be able to. Does it work with Xamarin instead of net6?

jeromelaban Jun 7, 2022
Maintainer

I'm also not able to reproduce the crash on the iOS app.

Daoting Jun 8, 2022
Author

Ok thanks.

Daoting · 2022-08-29T03:10:52Z

Daoting
Aug 29, 2022
Author

The VS Output window gives accurate bug locations after upgrading to VS17.3 Stable.

=================================================================
	Managed Stacktrace:
=================================================================
	  at <unknown> <0xffffffff>
	  at System.Threading.Monitor:try_enter_with_atomic_var <0x0002e>
	  at System.Threading.Monitor:ReliableEnterTimeout <0x00082>
	  at System.Threading.Monitor:Enter <0x0004c>
	  at Dt.Shell.IOS.BindableMetadataProvider:GetBindableTypeByType <0x0006e>
	  at Uno.UI.DataBinding.BindablePropertyDescriptor:GetPropertByBindableMetadataProvider <0x00026>

It ends up being caused by calling the BindableMetadataProvider:GetBindableTypeByType method.
This auto-generated code looks like this in the debug state:

The this.GetBindableTypeByFullName(type.FullName) method called internally is also fine. Crashes or deadlocks every time it reaches lock (knownMissingTypes).

I looked at the source code and didn't generate this code when it was in the release state. I tested it in the release state and never got this bug.

uno/src/SourceGenerators/Uno.UI.SourceGenerators/BindableTypeProviders/BindableTypeProvidersGenerationTask.cs

Line 644 in c94d459

writer.AppendLineInvariant(@"#if DEBUG");

I did the following:

downloaded uno4.4.5.zip, not found uno4.4.13;
run uno-4.4.5\build\convert-sourcetree-to-winui.cmd
commented out the code in two places

uno/src/SourceGenerators/Uno.UI.SourceGenerators/BindableTypeProviders/BindableTypeProvidersGenerationTask.cs

Line 228 in c94d459

writer.AppendLineInvariant(@"#if DEBUG");

uno/src/SourceGenerators/Uno.UI.SourceGenerators/BindableTypeProviders/BindableTypeProvidersGenerationTask.cs

Line 644 in c94d459

writer.AppendLineInvariant(@"#if DEBUG");

Build Uno.UI.SourceGenerators
Replace the two local files(Uno.UI.SourceGenerators.dll) in C:\Users\daoting.nuget\packages\uno.winui\4.4.13\

This will allow me to launch the app normally. But it is not the fundamental solution.

This error occurs after upgrading .NET 6.0. It exists on both Android and iOS. And it only appears when there are a lot of bindable types. My BindableMetadataProvider:GetBindableTypeByFullName method has 15064 lines of code.

I don't know how to circumvent this bug.

@jeromelaban Please help me, thank you very much!

7 replies

Daoting Aug 30, 2022
Author

I tried many more other methods.
This includes replacing List<Type> with ConcurrentBag<T> or ConcurrentDictionary<Type, string>. There are still bugs.

It turns out that as long as the _knownMissingTypes variable is defined, the application crashes even without other code. Even if there is no locking code. So I changed _knownMissingTypes to a static variable and everything was fine.

uno/src/SourceGenerators/Uno.UI.SourceGenerators/BindableTypeProviders/BindableTypeProvidersGenerationTask.cs

Line 229 in c94d459

    
           writer.AppendLineInvariant(@"private global::System.Collections.Generic.List<global::System.Type> _knownMissingTypes = new global::System.Collections.Generic.List<global::System.Type>();");

Changing it to static should have no effect to others. I've tested it many times on Android and iOS, and the app doesn't crash again.

Is it because there are too many member variables in BindableMetadataProvider class?

My BindableMetadataProvider class has 1127 member variables of type IBindableType. As I began to describe, there is no crash when there are few files(types).

@jeromelaban Do you think it can be updated like this? Thanks.

jeromelaban Aug 30, 2022
Maintainer

Thanks. This is likely hiding another issue, and it's unlikely to be root cause of the the runtime crash and even removing the types may just push the issue further away. It's probably best to open an issue in https://github.com/xamarin/xamarin-macios with this error [com.dt.samples] * Assertion: should not be reached at /__w/1/s/src/mono/mono/mini/../sgen/sgen-scan-object.h:91

Daoting Aug 31, 2022
Author

I've opened an issue in https://github.com/xamarin/xamarin-macios.

Now simply modify _knownMissingTypes to a static variable to stop crashing. This way should have no effect to others.

Please update it in the next version, otherwise it will be very troublesome every time.
@jeromelaban Please!

jeromelaban Aug 31, 2022
Maintainer

#9682 will provide a way to disable this specific part of the code, but it's likely that the issue will pop up in other locations.

Daoting Sep 1, 2022
Author

Great👍👍👍! Thanks!

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Help! The app crashes when it starts. #8933

Daoting May 31, 2022

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