Java.lang.ClassNotFoundException: Didn't find class "android.support.v7.widget.AlertDialogLayout"

[AnthonyLatty]

Xamarin.Android Version (eg: 6.0):

9.0

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

Mac OS 10.14.6

Support Libraries Version (eg: 23.3.0):

Upgraded from 28.0.0.1 to 28.0.0.3

Describe your Issue:

When using latest Xamarin.Android with support libraries 28.0.0.3 there is crash in "AlertDialogLayout" (strack trace below).

java.lang.ClassNotFoundException: Didn't find class "android.support.v7.widget.AlertDialogLayout" on path: DexPathList[[zip file "/system/framework/org.apache.http.legacy.boot.jar"

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

Update Visual Studio to latest stable.
Add project targeting API Level 28.
Add latest support libraries 28.0.0.3.
Create a Dialog
Run App.

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

dalvik.system.BaseDexClassLoader.findClass BaseDexClassLoader.java:134
java.lang.ClassLoader.loadClass ClassLoader.java:379
java.lang.ClassLoader.loadClass ClassLoader.java:312
android.view.LayoutInflater.createView LayoutInflater.java:606
android.view.LayoutInflater.createViewFromTag LayoutInflater.java:790
android.view.LayoutInflater.createViewFromTag LayoutInflater.java:730
android.view.LayoutInflater.inflate LayoutInflater.java:492
android.view.LayoutInflater.inflate LayoutInflater.java:423
android.view.LayoutInflater.inflate LayoutInflater.java:374
android.support.v7.app.AppCompatDelegateImpl.setContentView
android.support.v7.app.AppCompatDialog.setContentView
android.support.v7.app.AlertController.installContent
android.support.v7.app.AlertDialog.onCreate
android.app.Dialog.dispatchOnCreate Dialog.java:407
android.app.Dialog.show Dialog.java:302
android.support.v4.app.DialogFragment.onStart
android.support.v4.app.Fragment.performStart
android.support.v4.app.FragmentManagerImpl.moveToState
android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState
android.support.v4.app.FragmentManagerImpl.moveToState
android.support.v4.app.BackStackRecord.executeOps
android.support.v4.app.FragmentManagerImpl.executeOps
android.support.v4.app.FragmentManagerImpl.executeOpsTogether
android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute
android.support.v4.app.FragmentManagerImpl.execPendingActions
android.support.v4.app.FragmentManagerImpl$1.run
android.os.Handler.handleCallback Handler.java:873
android.os.Handler.dispatchMessage Handler.java:99
android.os.Looper.loop Looper.java:193
android.app.ActivityThread.main ActivityThread.java:6718
java.lang.reflect.Method.invoke Method.java
com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run RuntimeInit.java:493
com.android.internal.os.ZygoteInit.main ZygoteInit.java:858

[heromcp]

I have the same problem with Xamarin.Forms on release version.

FATAL EXCEPTION: main
Process: com.xxxxxxxx.movil, PID: 4377
android.view.InflateException: Binary XML file line #18: Binary XML file line #18: Error inflating class android.support.v7.widget.AlertDialogLayout

Caused by: android.view.InflateException: Binary XML file line #18: Error inflating class android.support.v7.widget.AlertDialogLayout

Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.v7.widget.AlertDialogLayout" on path: DexPathList[[zip file "/system/framework/org.apache.http.legacy.boot.jar", zip file "/data/app/com.phuyusalud.movil-MNIzraJSi4xxl05wRbOE5g==/base.apk"],nativeLibraryDirectories=[/data/app/com.phuyusalud.movil-MNIzraJSi4xxl05wRbOE5g==/lib/arm64, /system/fake-libs64, /data/app/com.phuyusalud.movil-MNIzraJSi4xxl05wRbOE5g==/base.apk!/lib/arm64-v8a, /system/lib64, /product/lib64]]

[Redth]

Are you using proguard/r8 and/or multidex?

You may need to add some rules to proguard/r8 to keep these classes if so

-keep android.support.v7.widget.AlertDialogLayout

[AnthonyLatty]

Where would you specify these rules for r8??

[StevenGranados]

Anyone encountering this issue, the line that worked for me was
-keep public class android.support.v7.widget.*

[mwerickson]

@StevenGranados I'm running into the same issue, where do you specify that rule?

[StevenGranados]

Create a file with the line in it and set the build action of the file to proguard configuration.

[mwerickson]

Thanks Steven! So, I'm guessing R8 also reads this config file?

[StevenGranados]

It works for me with r8 so I guess it does.

[swapnil591]

Getting error after adding proguard.cfg

[swapnil591]

Getting error after adding proguard.cfg

Solved
Make sure proguard.cfg file encoding is UTF-8

[eclipsed4utoo]

And if it's not obvious(like it wasn't to me when I added the file), also make sure you set the BuildAction to ProguardConfiguration.

[StevenGranados]

xamarin/Xamarin.Forms#9318
Might help with this issue in Forms 4.5.0