title: Didn't find class "androidx.core.content.FileProvider"
body: <p>I migrated my app to AndroidX and it's crashing on launch on API level 21. My application throws this exception:</p>
  
  <pre class="lang-none prettyprint-override"><code>10-08 09:42:50.930 11346-11346/com.example.test E/AndroidRuntime: FATAL EXCEPTION: main
  Process: com.example.test, PID: 11346
  java.lang.RuntimeException: Unable to get provider androidx.core.content.FileProvider: java.lang.ClassNotFoundException: Didn't find class "androidx.core.content.FileProvider" on path: DexPathList[[zip file "/data/app/com.example.test-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.test-1, /vendor/lib, /system/lib]]
      at android.app.ActivityThread.installProvider(ActivityThread.java:5121)
      at android.app.ActivityThread.installContentProviders(ActivityThread.java:4713)
      at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4596)
      at android.app.ActivityThread.access$1600(ActivityThread.java:169)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:146)
      at android.app.ActivityThread.main(ActivityThread.java:5487)
      at java.lang.reflect.Method.invokeNative(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:515)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
      at dalvik.system.NativeStart.main(Native Method)
   Caused by: java.lang.ClassNotFoundException: Didn't find class "androidx.core.content.FileProvider" on path: DexPathList[[zip file "/data/app/com.example.test.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.test-1, /vendor/lib, /system/lib]]
      at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:67)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
      at android.app.ActivityThread.installProvider(ActivityThread.java:5106)
      at android.app.ActivityThread.installContentProviders(ActivityThread.java:4713) 
      at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4596) 
      at android.app.ActivityThread.access$1600(ActivityThread.java:169) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:146) 
      at android.app.ActivityThread.main(ActivityThread.java:5487) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:515) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
      at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>And here is the <code>provider</code> definition in my AndroidManifest.xml file:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;provider
      android:name="androidx.core.content.FileProvider"
      android:authorities="${applicationId}.fileProvider"
      android:exported="false"
      android:grantUriPermissions="true"&gt;
      &lt;meta-data
          android:name="android.support.FILE_PROVIDER_PATHS"
          android:resource="@xml/provider_paths" /&gt;
  &lt;/provider&gt;
  </code></pre>
  
  <p>On the latest API level it works fine. Any suggestions would be useful, thanks in advance.</p>