Unity Android 6 Fragment $ InstantiationException

Recently (last few weeks) most of the Android users from my application started to suffer from crashes. UnityPlayerActivity failed to start with logged error:android.app.Fragment$InstantiationException.

Stack trace:

java.lang.RuntimeException: android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2450) android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:2510) android.app.ActivityThread.-wrap11 (ActivityThread.java 0) android .app.ActivityThread $ H.handleMessage (ActivityThread.java:1363)
android.os.Handler.dispatchMessage (Handler.java:102) android.os.Looper.loop (Looper.java:148) android.app.ActivityThread.main (ActivityThread.java:5461) java.lang.reflect.Method.invoke (Native Method: 0) com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:726) com.android.internal.os. ZygoteInit.main (ZygoteInit.java:616)

Caused: android.app.Fragment $ InstantiationException: android.app.Fragment.instantiate (Fragment.java:628) android.app.FragmentState.instantiate (Fragment.java:106) android.app.FragmentManagerImpl.restoreAllState (FragmentManager.java: 1858) android.app.FragmentController.restoreAllState (FragmentController.java:122) android.app.Activity.onCreate (Activity.java:918) com.unity3d.player.UnityPlayerActivity.onCreate (Unknown source: 0) android.app.Activity .performCreate (Activity.java:6251) android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1108) android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2403)

At the beginning my first thought was a permissions issue, but I cannot reproduce this error on any of my Android 6 devices, even if I deny permission (WRITE_EXTERNAL_STORAGE).

Is there any workaround for this issue (if this issue is common to Unity on Android 6)?

Thanks in advance!

PS: Unity version 5.5.0f3, Android version from squashed reports 6.0