[Xiaomi Mi 9 Questions & Answers] coderstory:
do this operate，settings app will fc ， if you use chinese or not english

open settings app -> network&internet ->mobile network -> advanced ->prederrd network type

logcat

04-09 23:36:20.414 929 988 E ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only

04-09 23:36:21.123 929 988 E ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only

04-09 23:36:22.286 929 988 E ANDR-PERF-MPCTL: Invalid profile no. 0, total profiles 0 only

04-09 23:36:22.491 9155 9155 E AndroidRuntime: FATAL EXCEPTION: main

04-09 23:36:22.491 9155 9155 E AndroidRuntime: Process: com.android.phone, PID: 9155

04-09 23:36:22.491 9155 9155 E AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:453)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.ArrayAdapter.getView(ArrayAdapter.java:415)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.AbsListView.obtainView(AbsListView.java:2366)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.ListView.measureHeightOfChildren(ListView.java:1408)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.ListView.onMeasure(ListView.java:1315)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at com.android.internal.widget.AlertDialogLayout.tryOnMeasure(AlertDialogLayout.java:144)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at com.android.internal.widget.AlertDialogLayout.onMeasure(AlertDialogLayout.java:69)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at com.android.internal.policy.DecorView.onMeasure(DecorView.java:716)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.View.measure(View.java:23169)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2718)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1545)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1855)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1460)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7183)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.Choreographer.doCallbacks(Choreographer.java:761)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.Choreographer.doFrame(Choreographer.java:696)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:873)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.os.Looper.loop(Looper.java:193)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6718)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)

04-09 23:36:22.491 9155 9155 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

04-09 23:36:22.529 3633 3796 E InputDispatcher: channel '80c4536 com.android.phone/com.android.phone.MobileNetworkSettings (server)' ~ Channel is unrecoverably broken and will be disposed!

04-09 23:36:22.530 3633 3796 E InputDispatcher: channel '7910fd4 com.android.phone/com.android.phone.MobileNetworkSettings (server)' ~ Channel is unrecoverably broken and will be disposed!

04-09 23:36:22.534 3633 9048 E ActivityManager: Service ServiceRecord{fca8b40 u0 com.android.phone/.vvm.RemoteVvmTaskManager} in process ProcessRecord{892ada0 9155:com.android.phone/1001} not same as in map: ServiceRecord{1b3e0e3 u0 com.android.phone/.vvm.RemoteVvmTaskManager}

04-09 23:36:22.535 3633 9048 E ActivityManager: Service ServiceRecord{f8b2b36 u0 com.android.stk/.StkAppService} in process ProcessRecord{892ada

and can you add a option to switch recent task and back button

thanks