今天突然报了一个很奇怪的错误，跳转Activity后，按返回键，就会崩溃，排查了半天，在此记录一下，希望对后续遇到同样的问题的童鞋有用。

java.lang.NoSuchFieldError: No field mActive of type Landroid/util/SparseArray;
 in class Landroidx/fragment/app/FragmentManagerImpl; 
 or its superclasses (declaration of 'androidx.fragment.app.FragmentManagerImpl' appears 
 in /data/app/com.adinnet.xlebike-nttDXl479eX57dOONE210A==/base.apk!classes2.dex)
        at androidx.fragment.app.FragmentationMagician.getActiveFragments(FragmentationMagician.java:153)
        at me.yokeyword.fragmentation.SupportHelper.getActiveFragment(SupportHelper.java:159)
        at me.yokeyword.fragmentation.SupportHelper.getActiveFragment(SupportHelper.java:131)
        at me.yokeyword.fragmentation.SupportActivityDelegate$1.run(SupportActivityDelegate.java:157)
        at me.yokeyword.fragmentation.queue.ActionQueue.handleAction(ActionQueue.java:53)
        at me.yokeyword.fragmentation.queue.ActionQueue.enqueueAction(ActionQueue.java:45)
        at me.yokeyword.fragmentation.queue.ActionQueue.access$000(ActionQueue.java:17)
        at me.yokeyword.fragmentation.queue.ActionQueue$1.run(ActionQueue.java:37)
        at android.os.Handler.handleCallback(Handler.java:794)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:176)
        at android.app.ActivityThread.main(ActivityThread.java:6651)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:824)

经排查后发现，和Android X的依赖项冲突有关。

方案一

根本原因是使用了第三方的Fragment的库，和Android X的Fragment产生了兼容性问题，不使用第三方的Fragment库即可 !

方案二

PS: 感谢评论区无无90的留言，给出了方案二:
是因为引用了me.yokeyword:fragmentation:1.3.6，GitHub给出了解决方案，引用me.yokeyword:fragmentationx:1.0.1版本即可。 GitHub链接:https://github.com/YoKeyword/Fragmentation/issues/1196