Setting TextBox.Foreground produces NullReferenceException on Android device

[s-beltz]

Current behavior

If setting TextBox.Foreground property Android devices will produce the following NullReferenceException:

Java.Lang.NoSuchFieldException   Message=No field mCursorDrawableRes in class Landroid/widget/TextView; (declaration of 'android.widget.TextView' appears in /system/framework/framework.jar!classes3.dex)
$exception    {System.NullReferenceException: Object reference not set to an instance of an object. 
at Windows.UI.Xaml.Controls.TextBoxView+EditTextCursorColorChanger.SetCursorColor (Android.Widget.EditText editText, Windows.UI.Color color) [0x00012] 
in C:\a\1\s\src\Uno.UI\UI\Xaml\Controls\TextBox\TextBoxView.Android.cs:162 }    System.NullReferenceException

Expected behavior

How to reproduce it (as minimally and precisely as possible)

Workaround

Environment

Nuget Package:

• Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia
• Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia
• Uno.SourceGenerationTasks
• Uno.UI.RemoteControl / Uno.WinUI.RemoteControl
• Other:

Nuget Package Version(s):
Uno.UI Version="3.6.0-dev.459"

Affected platform(s):

• iOS
• Android
• WebAssembly
• WebAssembly renderers for Xamarin.Forms
• macOS
• Skia
  • WPF
  • GTK (Linux)
  • Tizen
• Windows
• Build tasks
• Solution Templates

IDE:

• Visual Studio 2017 (version: )
• Visual Studio 2019 (version: 16.9.2)
• Visual Studio for Mac (version: )
• Rider Windows (version: )
• Rider macOS (version: )
• Visual Studio Code (version: )

Relevant plugins:

• Resharper (version: )

Anything else we need to know?

[kazo0]

@s-beltz Having trouble reproducing this one, does this result in an application crash? I see the code that is being referenced is wrapped in a try/catch so it shouldn't be throwing an exception.

Which version of the Uno.UI package are you using?

[s-beltz]

@kazo0 we observed this exception only on real hardware (Lenovo Tab M10) . The simulator does not show the exception. We last tested with Uno.UI "3.6.0-dev.459"

[ibebbs]

Also seeing this issue on physical hardware (Honor View 20) but I'm not [explicitly] setting the foreground. It happens just by having an empty <TextBox/> element in the XAML and seems to screw up subsequent layout of the page.

I've tried both v3.5.1 & v3.6.6 of Uno.UI.

A broader search provides a couple of hits related to Material design. Could it be related?

[davidjohnoliver]

@ibebbs Uno's Material implementation is all XAML-based, so it's probably not directly related to the other reports.

Can you post the exact stack trace you're getting? It's strange that it should interrupt the layout, since as @kazo0 said the attempt to set the native caret foreground is wrapped in a try/catch and it's expected that it should fail (harmlessly) on some devices.