diff --git a/src/DownKyi.Core/Storage/Database/Download/DownloadDb.cs b/src/DownKyi.Core/Storage/Database/Download/DownloadDb.cs
index f32c9c9..b4cf645 100644
--- a/src/DownKyi.Core/Storage/Database/Download/DownloadDb.cs
+++ b/src/DownKyi.Core/Storage/Database/Download/DownloadDb.cs
@@ -160,11 +160,11 @@ namespace DownKyi.Core.Storage.Database.Download
         {
             Dictionary<string, object> objects = new Dictionary<string, object>();
 
-            try
+            dbHelper.ExecuteQuery(sql, reader =>
             {
-                dbHelper.ExecuteQuery(sql, reader =>
+                while (reader.Read())
                 {
-                    while (reader.Read())
+                    try
                     {
                         // 读取字节数组
                         byte[] array = (byte[])reader["data"];
@@ -177,18 +177,17 @@ namespace DownKyi.Core.Storage.Database.Download
 
                         objects.Add((string)reader["id"], obj);
                     }
-                });
-            }
-            catch (Exception e)
-            {
-                Utils.Debugging.Console.PrintLine("Query()发生异常: {0}", e);
-                LogManager.Error($"{tableName}", e);
-            }
+                    catch (Exception e)
+                    {
+                        Utils.Debugging.Console.PrintLine("Query()发生异常: {0}", e);
+                        LogManager.Error($"{tableName}", e);
+                    }
+                }
+            });
 
             return objects;
         }
 
-
         /// <summary>
         /// 如果表不存在则创建表
         /// </summary>
diff --git a/src/DownKyi/Services/Download/AriaDownloadService.cs b/src/DownKyi/Services/Download/AriaDownloadService.cs
index cc32704..506dd4a 100644
--- a/src/DownKyi/Services/Download/AriaDownloadService.cs
+++ b/src/DownKyi/Services/Download/AriaDownloadService.cs
@@ -32,8 +32,8 @@ namespace DownKyi.Services.Download
     {
         private CancellationTokenSource tokenSource;
 
-        private int retry = 5;
-        private string nullMark = "<null>";
+        private readonly int retry = 5;
+        private readonly string nullMark = "<null>";
 
         public AriaDownloadService(ObservableCollection<DownloadingItem> downloadingList, ObservableCollection<DownloadedItem> downloadedList) : base(downloadingList, downloadedList)
         {
@@ -582,13 +582,13 @@ namespace DownKyi.Services.Download
                         for (int i = 0; i < retry; i++)
                         {
                             audioUid = DownloadAudio(downloading);
-                            if (audioUid != null && audioUid != "<null>")
+                            if (audioUid != null && audioUid != nullMark)
                             {
                                 break;
                             }
                         }
                     }
-                    if (audioUid == "<null>")
+                    if (audioUid == nullMark)
                     {
                         DownloadFailed(downloading);
                         return;
@@ -611,13 +611,13 @@ namespace DownKyi.Services.Download
                         for (int i = 0; i < retry; i++)
                         {
                             videoUid = DownloadVideo(downloading);
-                            if (videoUid != null && videoUid != "<null>")
+                            if (videoUid != null && videoUid != nullMark)
                             {
                                 break;
                             }
                         }
                     }
-                    if (videoUid == "<null>")
+                    if (videoUid == nullMark)
                     {
                         DownloadFailed(downloading);
                         return;
diff --git a/src/DownKyi/ViewModels/DownloadManager/DownloadedItem.cs b/src/DownKyi/ViewModels/DownloadManager/DownloadedItem.cs
index 0da70a4..15fd55f 100644
--- a/src/DownKyi/ViewModels/DownloadManager/DownloadedItem.cs
+++ b/src/DownKyi/ViewModels/DownloadManager/DownloadedItem.cs
@@ -84,6 +84,8 @@ namespace DownKyi.ViewModels.DownloadManager
         /// </summary>
         private void ExecuteOpenFolderCommand()
         {
+            if (DownloadBase == null) { return; }
+
             string videoPath = $"{DownloadBase.FilePath}.mp4";
             FileInfo fileInfo = new FileInfo(videoPath);
             if (File.Exists(fileInfo.FullName))
@@ -105,6 +107,8 @@ namespace DownKyi.ViewModels.DownloadManager
         /// </summary>
         private void ExecuteOpenVideoCommand()
         {
+            if (DownloadBase == null) { return; }
+
             string videoPath = $"{DownloadBase.FilePath}.mp4";
             var fileInfo = new FileInfo(videoPath);
             if (File.Exists(fileInfo.FullName))