diff --git a/app/src/main/java/jp/juggler/subwaytooter/DownloadReceiver.kt b/app/src/main/java/jp/juggler/subwaytooter/DownloadReceiver.kt
index 2472c49c..9ff08ebe 100644
--- a/app/src/main/java/jp/juggler/subwaytooter/DownloadReceiver.kt
+++ b/app/src/main/java/jp/juggler/subwaytooter/DownloadReceiver.kt
@@ -4,56 +4,60 @@ import android.app.DownloadManager
 import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
+import jp.juggler.util.LogCategory
 import jp.juggler.util.getIntOrNull
 import jp.juggler.util.getStringOrNull
 import jp.juggler.util.showToast
 
 class DownloadReceiver : BroadcastReceiver() {
+	
+	companion object {
+		private val log = LogCategory("DownloadReceiver")
+	}
+	
 	override fun onReceive(context : Context, intent : Intent?) {
-		intent ?: return
-		
-		val action = intent.action ?: return
-		
-		if(DownloadManager.ACTION_DOWNLOAD_COMPLETE == action) {
-			val id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0L)
-			
-			val downloadManager =
-				context.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager?
-					?: throw NotImplementedError("missing DownloadManager system service")
-			
-			val query = DownloadManager.Query().setFilterById(id)
-			downloadManager.query(query)?.use { cursor ->
-				if(cursor.moveToFirst()) {
-					
-					val title = cursor.getStringOrNull(DownloadManager.COLUMN_TITLE)
-					
-					if(DownloadManager.STATUS_SUCCESSFUL == cursor.getIntOrNull(DownloadManager.COLUMN_STATUS)) {
-						/*
-							ダウンロード完了通知がシステムからのものと重複することがある
+		when(intent?.action) {
+			DownloadManager.ACTION_DOWNLOAD_COMPLETE -> {
+				
+				val downloadManager =
+					context.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
+				
+				try {
+					val id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0L)
+					val query = DownloadManager.Query().setFilterById(id)
 
-							- (Aubee elm. Android 5.1) don't shows toast.
-							- (Samsung Galaxy S8+ Android 7.0) don't show toast.
-							- (Kyocera AndroidOne Android 8.0 S2) don't show toast.
-							- (LGE LGL24 Android 5.0.2) SHOWS toast.
-							- (LGE LGV32 Android 6.0) SHOWS toast.
-							
-							maybe it depends on customization by device maker. not depends on OS version.
-							
-							重複を回避する方法はなさそうだ…
-						*/
-						
-						showToast(
-							context,
-							false,
-							context.getString(R.string.download_complete, title)
-						)
-					} else {
-						showToast(
-							context,
-							false,
-							context.getString(R.string.download_failed, title)
-						)
+					downloadManager.query(query)?.use { cursor ->
+						if(! cursor.moveToFirst()) {
+							log.e("cursor.moveToFirst() failed.")
+						} else {
+							val title = cursor.getStringOrNull(DownloadManager.COLUMN_TITLE)
+							val status = cursor.getIntOrNull(DownloadManager.COLUMN_STATUS)
+							showToast(
+								context,
+								false,
+								if(status == DownloadManager.STATUS_SUCCESSFUL) {
+									context.getString(R.string.download_complete, title)
+								} else {
+									context.getString(R.string.download_failed, title)
+								}
+							)
+							/*
+								ダウンロード完了通知がシステムからのものと重複することがある
+	
+								- (Aubee elm. Android 5.1) don't shows toast.
+								- (Samsung Galaxy S8+ Android 7.0) don't show toast.
+								- (Kyocera AndroidOne Android 8.0 S2) don't show toast.
+								- (LGE LGL24 Android 5.0.2) SHOWS toast.
+								- (LGE LGV32 Android 6.0) SHOWS toast.
+								
+								maybe it depends on customization by device maker. not depends on OS version.
+								
+								重複を回避する方法はなさそうだ…
+							*/
+						}
 					}
+				} catch(ex : Throwable) {
+					log.e(ex, "downloadManager.query() failed.")
 				}
 			}
 		}