try to fix working of service on api 26+

android/AndroidManifest.xml

@@ -14,6 +14,7 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.READ_PHONE_STATE" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <!-- normal perm -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" /> <!-- required in API 26+ -->
     <application
         android:allowBackup="true"
         android:icon="@drawable/icon"

android/build.gradle

@@ -17,6 +17,10 @@ repositories {
     }
 }
 
+dependencies {
+    compile 'com.android.support:support-compat:28.0.0'
+}
+
 android {
     compileSdkVersion 28
     buildToolsVersion "28.0.1"

android/src/org/purplei2p/i2pd/ForegroundService.java

@@ -1,12 +1,17 @@
 package org.purplei2p.i2pd;
 
 import android.app.Notification;
+import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.app.Service;
+import android.content.Context;
 import android.content.Intent;
 import android.os.Binder;
+import android.os.Build;
 import android.os.IBinder;
+import android.support.annotation.RequiresApi;
+import android.support.v4.app.NotificationCompat;
 import android.util.Log;
 import android.widget.Toast;
 
@@ -104,9 +109,16 @@ public class ForegroundService extends Service {
         PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                 new Intent(this, I2PDActivity.class), 0);
 
+        // If earlier version channel ID is not used
+        // https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
+        String channelId = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) ? createNotificationChannel() : "";
+
         // Set the info for the views that show in the notification panel.
-        Notification notification = new Notification.Builder(this)
+        Notification notification = new NotificationCompat.Builder(this, channelId)
+                .setOngoing(true)
                 .setSmallIcon(R.drawable.itoopie_notification_icon) // the status icon
+                .setPriority(Notification.PRIORITY_DEFAULT)
+                .setCategory(Notification.CATEGORY_SERVICE)
                 .setTicker(text) // the status text
                 .setWhen(System.currentTimeMillis()) // the time stamp
                 .setContentTitle(getText(R.string.app_name)) // the label of the entry
@@ -120,6 +132,18 @@ public class ForegroundService extends Service {
         shown = true;
     }
 
+    @RequiresApi(Build.VERSION_CODES.O)
+    private synchronized String createNotificationChannel() {
+        String channelId = getString(R.string.app_name);
+        CharSequence channelName = "I2Pd service";
+        NotificationChannel chan = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_LOW);
+        //chan.setLightColor(Color.PURPLE);
+        chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
+        NotificationManager service = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
+        service.createNotificationChannel(chan);
+        return channelId;
+    }
+
     private static final DaemonSingleton daemon = DaemonSingleton.getInstance();
 }