Beginning with Android 8.0 (API level 26), the system imposes additional restrictions on manifest-declared receivers. If your app targets API level 26 or higher, you cannot use the manifest to declare a receiver for most implicit broadcasts (broadcasts that do not target your app specifically).

意思静态注册的广播在8.0以上是不能用，推荐用代码注册广播。
解决方案可以这么做：

配置：

<receiver android:name="MyStart">

    <intent-filter>
        <action android:name="com.example.y.myapplication" />
    </intent-filter>
</receiver>
代码：

Intent intent = new Intent();

                intent.setComponent(new ComponentName("com.example.y.myapplication","com.example.y.myapplication.MyStart"));

                getApplicationContext().sendBroadcast(intent);