Error: null_class_ptr_read_c0000005_windows.ui.xaml.dll!ccontentroot::getvisualidentifier

Question

Error: null_class_ptr_read_c0000005_windows.ui.xaml.dll!ccontentroot::getvisualidentifier

Henrik Barna 51

Hello,

I have an UWP app available on PC and desktop. Recently, I have updated the app and realized there are daily hundreds of thousands crashes on Xbox can be found in Partner Center Health report. I am using AppCenter and it doesn't report any problem. After hours I could learn that the problem could be in the background process which is not supported by the AppCenter.

I have downloaded the minidumb and opened with Visual Studio where I could find the following information:
Process name: backgroundTaskHost.exe
Exception code: 0xC0000005
Exception information: The thread tried to read from or write to a virtual address for which it does not have the appropriate access.

I can not debug with mixed because I get the following error:
... The matching version of mrt100.dll could not be found on the Microsoft symbol server...

All I did in this recent update is the following:

Updates Microsoft.UI to ver 2.7
Changed IBackgroundTask to XamlRenderingBackgroundTask (Xbox not using any methods requiring XamlRendering, just the PC version)

I know this is not too much information, all I would like to ask to give me some tips to start figuring out what could cause the crash.

Thank you so much in advance.

Henrik

Anonymous

2021-11-11T06:05:37.593+00:00

Hi @Henrik Barna , would you mind telling me that if this issue happens on both PC and Xbox or it only happens on Xbox?
Henrik Barna 51 Reputation points

2021-11-11T10:35:06.997+00:00

Only on xbox
Anonymous

2021-11-18T01:21:46.897+00:00

I'm asking other engineers about this issue. I'll come back once I got something new.
Anonymous

2021-11-18T06:39:39.69+00:00

@Henrik Barna Could you please tell me what are you doing in the background task? Based on your description, it used to work correctly, right? What have you changed in the background task?
Henrik Barna 51 Reputation points

2021-11-22T20:08:36.99+00:00

I have a background task which changes the desktop wallpaper periodically. The background task worked correctly before the update. With the last update I made a new function but only on PC. Because of this change I had to change the background task to XamlRenderingBackgroundTask.

This is the change I've made and updated WinUI to ver 2.7.

Now I created a separate background task for Xbox which is IBackgroundTask again and doesn't contain any new code. (So I basically reverted the background task on Xbox).

However, this is not solved the problem I have more than 400K crashes daily.
Anonymous

2021-11-23T06:46:24.08+00:00

@Henrik Barna OK, I got that. So now you are having a separate background task that is the same as what you do before the update now, right? Would you please share the code that you've used in the background task for Xbox? We need more information about what exactly the app is doing.
Henrik Barna 51 Reputation points

2021-11-30T12:05:20.21+00:00

I have attached a txt file which includes the background task code. (Please tell me if any other classes are needed)

However, as you can see I have managed not to reference any WinUI component in this background task which is created only for Xbox. Despite that I get approx 400K crashes from the Xbox app daily what is insane. :) I don't even has that much users to create this amount of crashes.

153705-xboxslideshowtask.txt
Anonymous

2021-12-02T09:55:22.973+00:00

I don't have an Xbox here so I can't test the code now. But I take a look at your code, what is the WallpaperCollection?

Henrik Barna 51

The following class:

public sealed class WallpaperCollection
    {
        public string CollectionType { get; set; }
        public string CollectionSubType { get; set; }
        public DateTimeOffset CollectionDate { get; set; }
        public string PreviousWallpaperPhotoUrl { get; set; }
        public string PublisherId { get; set; }
        public string UserId { get; set; }
        public int IsLockScreen { get; set; }
    }