Xamarin.forms: Adding sound resource to Android project leads to NullReferenceException on LoadApplication()

[BioTurboNick]

Description

Adding sound resource to Android project as described in (https://developer.xamarin.com/recipes/android/media/audio/play_audio/) leads to NullReferenceException on LoadApplication().
(unclear if it has to be a sound file, but that's what I was using)

Steps to Reproduce

1. Make a new Xamarin Cross-platform project (.Net Standard, Forms, Android project only)
2. Add a sound file (.m4a) to the "raw" directory under "resources" in the Android project
3. Set the build action of the file to "AndroidResource" and let the code generator work
4. Build and run the application.
5. Crash with "NullReferenceException" in the LoadApplication line in MainActivity.
6. Delete the sound file.
7. Rebuild and run.
8. No crash.

Expected Behavior

Application should build and run regardless of changes to the resources directory.

Actual Behavior

Application crashes in non-user code on launch.

Basic Information

• Version with issue: 2.5.0.122203
• Last known good version: Unknown, tried back through 2.4.x
• IDE: Visual Studio 2017 15.5.4
• Platform Target Frameworks:
  
  
  
  • Android: 8.0
  
  
• Android Support Library Version: 25.4.0.2
• Nuget Packages: none
• Affected Devices: x86 API25 emulator

Reproduction Link

AndroidResourceBug.zip

[hartez]

@BioTurboNick What's the name of the .m4a file? (I ask because Android resource generation restricts the valid characters in a resource name.)

[BioTurboNick]

"dial_click.m4a" The Resource.Designer.cs generated correctly (AFAICT). I removed the underscore though and it still crashes.

[BioTurboNick]

For comparison, adding a sound as an Asset with build action AndroidAsset as described here (https://blog.xamarin.com/adding-sound-xamarin-forms-app/) works.

[StephaneDelcroix]

As, per step 0, you can trigger this issue on projects not involving Xamarin.Forms, please file this issue against Xamarin Android project.

[BioTurboNick]

@StephaneDelcroix

That is not what step 0 says. It is occurring in LoadApplication(new App()), which is Xamarin.Forms code. Please reopen this issue.

[StephaneDelcroix]

I read it wrong. Please attach a small reproduction project.

[BioTurboNick]

Reproduction project:

AndroidResourceBug.zip

[BioTurboNick]

Another observation: installing the NuGet package XFShapeView, which amends Resource.Designer.cs, also causes this crash.

[marcojak]

Same problem here but I don't think it's directly related to the resource sound file.
I don't have such file but I get the same error and I'm reading more and more people online having the same issue.

I suspect it's something related to Xamarin Forms and .Netstandard

[PureWeen]

I ran the reproduction project from VS 15.5.6 with the latest Xam Forms 2.5.0.122203 and didn't get any exceptions. Also tried on VS For Mac and didn't get any exceptions. I also installed XFShapeView and didn't see any issues
AndroidResourceBug.zip

I'm attaching a version of the repro that has the SLN file as the original seems to be missing it

[PureWeen]

Alright I spoke too soon. I was able to reproduce by adding and removing the m4a a few times. Though this still feels like it might be a tooling issue and not a Xamarin Forms issue. If I remove or add the m4a file and then run the project right away I get the nullreference exception. But if I just rebuild the project or delete the bin/obj folders then I don't get a null reference exception. So this seems to occur because of files that don't detect they need to be rebuilt

[BioTurboNick]

I can confirm that Rebuild appears to correct the problem. Thank you for pointing that out.

Workaround: Every time a resource is added, perform a Rebuild on the Android project (and/or delete bin and obj folders).

[dellis1972]

Adb Logcat output below.
So the null ref exception is happening at [1].
Looking at the Resource.Designer.cs file the raw output is correctly added and removed from that file when it is removed/add to/from the project. The file is correctly removed and added to the zip.
The assembly is also being fast deployed and does not contain the resource in its compiled code.
I cannot repo in a non Xamarin.Forms Android app. So I'm not sure what is happening here, the android build system, packaging and fast deployment all appear to be doing the right thing.
[1] https://github.com/xamarin/Xamarin.Forms/blob/e65b48b7194aff9287aae8619a3964fbf71993fe/Xamarin.Forms.Platform.Android/AppCompat/FormsAppCompatActivity.cs#L291

I/MonoDroid( 2774): UNHANDLED EXCEPTION:
I/MonoDroid( 2774): System.NullReferenceException: Object reference not set to an instance of an object
I/MonoDroid( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.InternalSetPage (Xamarin.Forms.Page page) [0x0006f] in :0
I/MonoDroid( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.SetMainPage () [0x0000c] in :0
I/MonoDroid( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.LoadApplication (Xamarin.Forms.Application application) [0x0025c] in :0
I/MonoDroid( 2774): at App1.Droid.MainActivity.OnCreate (Android.OS.Bundle bundle) [0x0002d] in :0
I/MonoDroid( 2774): at Android.Support.V4.App.FragmentActivity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x0000f] in <1e89c43d3c7d48b5ba69bfc0b1bdf114>:0
I/MonoDroid( 2774): at (wrapper dynamic-method) System.Object.f5ffd162-ce4a-4512-95d6-42c9a204eff2(intptr,intptr,intptr)
W/art ( 2774): JNI RegisterNativeMethods: attempt to register 0 native methods for android.runtime.JavaProxyThrowable
D/Mono ( 2774): DllImport searching in: '__Internal' ('(null)').
D/Mono ( 2774): Searching for 'java_interop_jnienv_throw'.
D/Mono ( 2774): Probing 'java_interop_jnienv_throw'.
D/Mono ( 2774): Found as 'java_interop_jnienv_throw'.
D/AndroidRuntime( 2774): Shutting down VM
--------- beginning of crash
E/AndroidRuntime( 2774): FATAL EXCEPTION: main
E/AndroidRuntime( 2774): Process: com.companyname.App1, PID: 2774
E/AndroidRuntime( 2774): android.runtime.JavaProxyThrowable: System.NullReferenceException: Object reference not set to an instance of an object
E/AndroidRuntime( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.InternalSetPage (Xamarin.Forms.Page page) [0x0006f] in :0
E/AndroidRuntime( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.SetMainPage () [0x0000c] in :0
E/AndroidRuntime( 2774): at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.LoadApplication (Xamarin.Forms.Application application) [0x0025c] in :0
E/AndroidRuntime( 2774): at App1.Droid.MainActivity.OnCreate (Android.OS.Bundle bundle) [0x0002d] in :0
E/AndroidRuntime( 2774): at Android.Support.V4.App.FragmentActivity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x0000f] in <1e89c43d3c7d48b5ba69bfc0b1bdf114>:0
E/AndroidRuntime( 2774): at (wrapper dynamic-method) System.Object.f5ffd162-ce4a-4512-95d6-42c9a204eff2(intptr,intptr,intptr)
E/AndroidRuntime( 2774): at md58adf3f2592a7497b73592b5e766304c2.MainActivity.n_onCreate(Native Method)
E/AndroidRuntime( 2774): at md58adf3f2592a7497b73592b5e766304c2.MainActivity.onCreate(MainActivity.java:29)
E/AndroidRuntime( 2774): at android.app.Activity.performCreate(Activity.java:5937)
E/AndroidRuntime( 2774): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
E/AndroidRuntime( 2774): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
E/AndroidRuntime( 2774): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
E/AndroidRuntime( 2774): at android.app.ActivityThread.access$800(ActivityThread.java:144)
E/AndroidRuntime( 2774): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
E/AndroidRuntime( 2774): at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime( 2774): at android.os.Looper.loop(Looper.java:135)
E/AndroidRuntime( 2774): at android.app.ActivityThread.main(ActivityThread.java:5221)
E/AndroidRuntime( 2774): at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime( 2774): at java.lang.reflect.Method.invoke(Method.java:372)
E/AndroidRuntime( 2774): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
E/AndroidRuntime( 2774): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
W/ActivityManager( 1512): Force finishing activity com.companyname.App1/md58adf3f2592a7497b73592b5e766304c2.MainActivity

[samhouts]

Improvement have been made with Android resources and bin/obj problems in the last few months. I'm willing to bet that this is no longer an issue. If I am wrong and you are still experiencing this, please feel free to reopen it! Thank you!