命令'；adb shell dumpsys netstats'；在Android API 21,22,23上引发NullPointerException

当我在Genymotion中使用API 21、22和23在Android模拟器上运行此命令时

adb shell dumpsys netstats

我得到以下输出：

Active interfaces:
Active UID interfaces:
Dev stats:

    Exception occurred while dumping:
    java.lang.NullPointerException: Attempt to invoke virtual method 'void com.android.server.net.NetworkStatsRecorder.dumpLocked(com.android.internal.util.IndentingPrintWriter, boolean)' on a null object reference
        at com.android.server.net.NetworkStatsService.dump(NetworkStatsService.java:1226)
        at android.os.Binder.doDump(Binder.java:355)
        at android.os.Binder.dump(Binder.java:342)
        at android.os.Binder.onTransact(Binder.java:293)
        at android.net.INetworkStatsService$Stub.onTransact(INetworkStatsService.java:155)
        at android.os.Binder.execTransact(Binder.java:507)

这一异常的原因可能是什么？其他dumpsys命令工作正常