Could not load file or assembly 'Xamarin.AndroidX.AppCompat.Resources'

Xamarin.Android Version (eg: 6.0):

Version: 10.1.3.7

Operating System & Version (eg: Mac OSX 10.11):

Mac OSX 10.15.2

Support Libraries Version (eg: 23.3.0):

28.0.3

Describe your Issue:

It works well until previous version a few days ago, but build error occurs today, then I upgrade dependency libraries to the newest, error changes to:

<PackageReference Include="Xamarin.AndroidX.Migration">
      <Version>1.0.0-preview05</Version>
      <Version>1.0.0-rc1</Version>
</PackageReference>

[MonoDroid] System.IO.FileNotFoundException: Could not load file or assembly 'Xamarin.AndroidX.AppCompat.Resources, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies.
[MonoDroid] File name: 'Xamarin.AndroidX.AppCompat.Resources, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'
[MonoDroid]   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1[TResult].Start[TStateMachine] (TStateMachine& stateMachine) [0x0002c] in <6b940a667a274fa48104ab71b2541709>:0 
[MonoDroid]   at Xamarin.Forms.Platform.Android.ResourceManager.GetFormsDrawableAsync (Android.Content.Context context, Xamarin.Forms.ImageSource imageSource, System.Threading.CancellationToken cancellationToken) [0x00033] in <a38b08ed6ae34fcca788cdc23b3fac01>:0 
[MonoDroid]   at Xamarin.Forms.Platform.Android.BottomNavigationViewUtils.SetMenuItemIcon (Android.Views.IMenuItem menuItem, Xamarin.Forms.ImageSource source, Android.Content.Context context) [0x00017] in <a38b08ed6ae34fcca788cdc23b3fac01>:0 
[MonoDroid]   at Xamarin.Forms.Platform.Android.BottomNavigationViewUtils.SetupMenu (Android.Views.IMenu menu, System.Int32 maxBottomItems, System.Collections.Generic.List`1[T] items, System.Int32 currentIndex, Google.Android.Material.BottomNavigation.BottomNavigationView bottomView, Android.Content.Context context) [0x001c8] in <a38b08ed6ae34fcca788cdc23b3fac01>:0 
[MonoDroid]   at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.<ThrowAsync>b__7_0 (System.Object state) [0x00000] in <6b940a667a274fa48104ab71b2541709>:0 
[MonoDroid]   at Android.App.SyncContext+<>c__DisplayClass2_0.<Post>b__0 () [0x00000] in <78bc2a97e5be434ba8d7b494fe3c28fb>:0 
[MonoDroid]   at Java.Lang.Thread+RunnableImplementor.Run () [0x00008] in <78bc2a97e5be434ba8d7b494fe3c28fb>:0 
[MonoDroid]   at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00009] in <78bc2a97e5be434ba8d7b494fe3c28fb>:0 
[MonoDroid]   at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.44(intptr,intptr)

Steps to Reproduce (with link to sample solution if possible):

Include any relevant Exception Stack traces, build logs, adb logs:

[moljac]

Yes. Older stale projects can produce issues.

General guidelines:

1. Migrate from packages.config to <PackageReference />

   Visual Studio for Windows has option for migration.

2. Update all packagest to latest versions and test application

   Manage NuGet packages for Solution in Visual Studio for Windows can consolidate all packages for solution.

3. Change options for Android application (all configurations) [TODO]

   1. aapt2

   2. d8

   3. r8

4. Add Xamarin.AndroidX.Migration package to the Android application and rebuild.

5. Fix issues reported by migration package (packages)

   In Visual Studio for Windows unload project and edit project file (*.csproj) by adding code snippet from migration package error.

   In Visual Studio for Mac unloading is not necessary - project files can be edited directly.

6. Save, load/reload and rebuild application

   This step will most likely fail with numerous errors due to source code not being migrated (namespaces, fully qualified typenames).

7. Fix source code (build errors) from step 5.

   This is manual step where Android.Support namespaces and [fully qualified] typenames must be replaced with AndroidX counterparts. Use tooltips available in both IDEs (Visual Studio for Windows and Mac).

   Do not forget migrating Android.Support packagenames in layout files (*.axml). Failing to do so will cause runtime errors (inflation of binary XML file).

   Mapping file (for search and replace):

   https://github.com/xamarin/AndroidX/blob/master/mappings/androidx-mapping.csv

also here

https://github.com/xamarin/XamarinAndroidXMigration/pull/34

[Nikituh]

I would like to point out that I was also experiencing this issue, tried everything, without any avail. It has something to do with older project configurations. For Example, the old project did not have packages.config, various differences in the .csproj file.

The solution I found was to create a new project, add all the same dependencies, copy over all the code and voilà, unable to reproduce the issue.