ClassNotFoundException after adding Ion library in Android 4.4 (19)

Question

After adding the Ion library to my project, I can't start my app in Android 4.4, everything higher works fine.

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.swe.gruppe4.mockup2, PID: 3281
              java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.swe.gruppe4.mockup2/com.swe.gruppe4.mockup2.LoginActivity}: java.lang.ClassNotFoundException: Didn't find class "com.swe.gruppe4.mockup2.LoginActivity" on path: DexPathList[[zip file "/data/app/com.swe.gruppe4.mockup2-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.swe.gruppe4.mockup2-2, /vendor/lib, /system/lib]]
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
                  at android.app.ActivityThread.access$800(ActivityThread.java:135)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:136)
                  at android.app.ActivityThread.main(ActivityThread.java:5017)
                  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:779)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
                  at dalvik.system.NativeStart.main(Native Method)
               Caused by: java.lang.ClassNotFoundException: Didn't find class "com.swe.gruppe4.mockup2.LoginActivity" on path: DexPathList[[zip file "/data/app/com.swe.gruppe4.mockup2-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.swe.gruppe4.mockup2-2, /vendor/lib, /system/lib]]
                  at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
                  at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
                  at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
                  at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
                  at android.app.ActivityThread.access$800(ActivityThread.java:135) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:136) 
                  at android.app.ActivityThread.main(ActivityThread.java:5017) 
                  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:779) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
                  at dalvik.system.NativeStart.main(Native Method) 
Application terminated.

I added Ion through the app's build.gradle as it is stated on the github, compile 'com.koushikdutta.ion:ion:2.+'.

As stated earlier, on higher Android versions it works fine. It also works fine on a completely clean project with just adding Ion

Answer 1

I now fixed it myself. I created a new project with the same package name and copied the app folder completely to the new project, it works fine there. Weird!