diff --git a/BililiveRecorder.Core/Api/Danmaku/DanmakuClient.cs b/BililiveRecorder.Core/Api/Danmaku/DanmakuClient.cs
index 3d93fac..ac2ccc4 100644
--- a/BililiveRecorder.Core/Api/Danmaku/DanmakuClient.cs
+++ b/BililiveRecorder.Core/Api/Danmaku/DanmakuClient.cs
@@ -153,7 +153,7 @@ namespace BililiveRecorder.Core.Api.Danmaku
         }
 
 #pragma warning disable VSTHRD100 // Avoid async void methods
-        private async void SendPingMessageTimerCallback(object sender, ElapsedEventArgs e)
+        private async void SendPingMessageTimerCallback(object? sender, ElapsedEventArgs e)
 #pragma warning restore VSTHRD100 // Avoid async void methods
         {
             try
@@ -248,9 +248,9 @@ namespace BililiveRecorder.Core.Api.Danmaku
             if (this.danmakuTransport is not { } transport)
                 return;
 
-            var playload = ((body?.Length ?? 0) > 0) ? Encoding.UTF8.GetBytes(body) : Array.Empty<byte>();
+            var payload = Encoding.UTF8.GetBytes(body);
             const int headerLength = 16;
-            var totalLength = playload.Length + headerLength;
+            var totalLength = payload.Length + headerLength;
 
             var buffer = ArrayPool<byte>.Shared.Rent(totalLength);
             try
@@ -261,8 +261,8 @@ namespace BililiveRecorder.Core.Api.Danmaku
                 BinaryPrimitives.WriteUInt32BigEndian(new Span<byte>(buffer, 8, 4), (uint)action);
                 BinaryPrimitives.WriteUInt32BigEndian(new Span<byte>(buffer, 12, 4), 1);
 
-                if (playload.Length > 0)
-                    Array.Copy(playload, 0, buffer, headerLength, playload.Length);
+                if (payload.Length > 0)
+                    Array.Copy(payload, 0, buffer, headerLength, payload.Length);
 
                 await transport.SendAsync(buffer, 0, totalLength).ConfigureAwait(false);
             }
diff --git a/BililiveRecorder.Core/Api/Http/HttpApiClient.cs b/BililiveRecorder.Core/Api/Http/HttpApiClient.cs
index 3997901..ce971c5 100644
--- a/BililiveRecorder.Core/Api/Http/HttpApiClient.cs
+++ b/BililiveRecorder.Core/Api/Http/HttpApiClient.cs
@@ -77,7 +77,7 @@ namespace BililiveRecorder.Core.Api.Http
             old?.Dispose();
         }
 
-        private void Config_PropertyChanged(object sender, PropertyChangedEventArgs e)
+        private void Config_PropertyChanged(object? sender, PropertyChangedEventArgs e)
         {
             if (e.PropertyName is (nameof(this.config.Cookie)) or (nameof(this.config.TimingApiTimeout)))
                 this.UpdateHttpClient();
diff --git a/BililiveRecorder.Core/Config/ConfigParser.cs b/BililiveRecorder.Core/Config/ConfigParser.cs
index 31ba787..61df8e6 100644
--- a/BililiveRecorder.Core/Config/ConfigParser.cs
+++ b/BililiveRecorder.Core/Config/ConfigParser.cs
@@ -155,7 +155,7 @@ namespace BililiveRecorder.Core.Config
 
             var ext = Path.GetExtension(path);
 
-            var tempPath = Path.Combine(Path.GetDirectoryName(path), Path.ChangeExtension(path, RandomString(6) + ext));
+            var tempPath = Path.Combine(Path.GetDirectoryName(path)!, Path.ChangeExtension(path, RandomString(6) + ext));
             var backupPath = Path.ChangeExtension(path, "backup" + ext);
 
             // delete any existing backups
diff --git a/BililiveRecorder.Core/Danmaku/BasicDanmakuWriter.cs b/BililiveRecorder.Core/Danmaku/BasicDanmakuWriter.cs
index d4e2063..d1939a4 100644
--- a/BililiveRecorder.Core/Danmaku/BasicDanmakuWriter.cs
+++ b/BililiveRecorder.Core/Danmaku/BasicDanmakuWriter.cs
@@ -58,7 +58,7 @@ namespace BililiveRecorder.Core.Danmaku
                     this.xmlWriter = null;
                 }
 
-                try { Directory.CreateDirectory(Path.GetDirectoryName(path)); } catch (Exception) { }
+                try { Directory.CreateDirectory(Path.GetDirectoryName(path)!); } catch (Exception) { }
                 var stream = File.Open(path, FileMode.Create, FileAccess.Write, FileShare.Read);
 
                 this.config = room.RoomConfig;
diff --git a/BililiveRecorder.Core/Recorder.cs b/BililiveRecorder.Core/Recorder.cs
index 2006558..99c441c 100644
--- a/BililiveRecorder.Core/Recorder.cs
+++ b/BililiveRecorder.Core/Recorder.cs
@@ -125,48 +125,48 @@ namespace BililiveRecorder.Core
 
         #region Events
 
-        private void Room_IOStats(object sender, IOStatsEventArgs e)
+        private void Room_IOStats(object? sender, IOStatsEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             IOStats?.Invoke(this, new AggregatedRoomEventArgs<IOStatsEventArgs>(room, e));
         }
 
-        private void Room_RecordingStats(object sender, RecordingStatsEventArgs e)
+        private void Room_RecordingStats(object? sender, RecordingStatsEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             RecordingStats?.Invoke(this, new AggregatedRoomEventArgs<RecordingStatsEventArgs>(room, e));
         }
 
-        private void Room_RecordFileClosed(object sender, RecordFileClosedEventArgs e)
+        private void Room_RecordFileClosed(object? sender, RecordFileClosedEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             _ = Task.Run(async () => await this.basicWebhookV2.SendFileClosedAsync(e).ConfigureAwait(false));
             _ = Task.Run(async () => await this.basicWebhookV1.SendAsync(new RecordEndData(e)).ConfigureAwait(false));
             RecordFileClosed?.Invoke(this, new AggregatedRoomEventArgs<RecordFileClosedEventArgs>(room, e));
         }
 
-        private void Room_RecordFileOpening(object sender, RecordFileOpeningEventArgs e)
+        private void Room_RecordFileOpening(object? sender, RecordFileOpeningEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             _ = Task.Run(async () => await this.basicWebhookV2.SendFileOpeningAsync(e).ConfigureAwait(false));
             RecordFileOpening?.Invoke(this, new AggregatedRoomEventArgs<RecordFileOpeningEventArgs>(room, e));
         }
 
-        private void Room_RecordSessionStarted(object sender, RecordSessionStartedEventArgs e)
+        private void Room_RecordSessionStarted(object? sender, RecordSessionStartedEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             _ = Task.Run(async () => await this.basicWebhookV2.SendSessionStartedAsync(e).ConfigureAwait(false));
             RecordSessionStarted?.Invoke(this, new AggregatedRoomEventArgs<RecordSessionStartedEventArgs>(room, e));
         }
 
-        private void Room_RecordSessionEnded(object sender, RecordSessionEndedEventArgs e)
+        private void Room_RecordSessionEnded(object? sender, RecordSessionEndedEventArgs e)
         {
-            var room = (IRoom)sender;
+            if (sender is not IRoom room) return;
             _ = Task.Run(async () => await this.basicWebhookV2.SendSessionEndedAsync(e).ConfigureAwait(false));
             RecordSessionEnded?.Invoke(this, new AggregatedRoomEventArgs<RecordSessionEndedEventArgs>(room, e));
         }
 
-        private void Room_PropertyChanged(object sender, PropertyChangedEventArgs e)
+        private void Room_PropertyChanged(object? sender, PropertyChangedEventArgs e)
         {
             if (sender is not IRoom room)
                 return;
diff --git a/BililiveRecorder.Core/Recording/RawDataRecordTask.cs b/BililiveRecorder.Core/Recording/RawDataRecordTask.cs
index c005114..b451cc6 100644
--- a/BililiveRecorder.Core/Recording/RawDataRecordTask.cs
+++ b/BililiveRecorder.Core/Recording/RawDataRecordTask.cs
@@ -31,7 +31,7 @@ namespace BililiveRecorder.Core.Recording
             var (fullPath, relativePath) = this.CreateFileName();
 
             try
-            { Directory.CreateDirectory(Path.GetDirectoryName(fullPath)); }
+            { Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!); }
             catch (Exception) { }
 
             this.fileOpeningEventArgs = new RecordFileOpeningEventArgs(this.room)
@@ -110,12 +110,24 @@ namespace BililiveRecorder.Core.Recording
                     recordFileClosedEvent = null;
 
                 try
-                { file.Dispose(); }
+                {
+#if NET6_0_OR_GREATER
+                    await file.DisposeAsync();
+#else
+                    file.Dispose();
+#endif
+                }
                 catch (Exception ex)
                 { this.logger.Warning(ex, "关闭文件时发生错误"); }
 
                 try
-                { stream.Dispose(); }
+                {
+#if NET6_0_OR_GREATER
+                    await stream.DisposeAsync();
+#else
+                    stream.Dispose();
+#endif
+                }
                 catch (Exception) { }
 
                 try
diff --git a/BililiveRecorder.Core/Recording/RecordTaskBase.cs b/BililiveRecorder.Core/Recording/RecordTaskBase.cs
index 1c98620..90c666c 100644
--- a/BililiveRecorder.Core/Recording/RecordTaskBase.cs
+++ b/BililiveRecorder.Core/Recording/RecordTaskBase.cs
@@ -115,9 +115,19 @@ namespace BililiveRecorder.Core.Recording
             {
                 try
                 {
+                    if (state is not WeakReference<Stream> weakRef)
+                        return;
+
                     await Task.Delay(1000);
-                    if (((WeakReference<Stream>)state).TryGetTarget(out var weakStream))
+
+                    if (weakRef.TryGetTarget(out var weakStream))
+                    {
+#if NET6_0_OR_GREATER
+                        await weakStream.DisposeAsync();
+#else
                         weakStream.Dispose();
+#endif
+                    }
                 }
                 catch (Exception)
                 { }
@@ -128,7 +138,7 @@ namespace BililiveRecorder.Core.Recording
 
         protected abstract void StartRecordingLoop(Stream stream);
 
-        private void Timer_Elapsed_TriggerIOStats(object sender, ElapsedEventArgs e)
+        private void Timer_Elapsed_TriggerIOStats(object? sender, ElapsedEventArgs e)
         {
             int networkDownloadBytes, diskWriteBytes;
             TimeSpan durationDiff, diskWriteDuration;
@@ -161,7 +171,7 @@ namespace BililiveRecorder.Core.Recording
 
             this.OnIOStats(new IOStatsEventArgs
             {
-                StreamHost = streamHost,
+                StreamHost = this.streamHost,
                 NetworkBytesDownloaded = networkDownloadBytes,
                 Duration = durationDiff,
                 StartTime = startTime,
@@ -253,7 +263,7 @@ namespace BililiveRecorder.Core.Recording
             this.logger.Information("没有符合设置要求的画质，稍后再试。设置画质 {QnSettings}, 可用画质 {AcceptQn}", qns, codecItem.AcceptQn);
             throw new NoMatchingQnValueException();
 
-        match_qn_success:
+match_qn_success:
             this.logger.Debug("设置画质 {QnSettings}, 可用画质 {AcceptQn}, 最终选择 {SelectedQn}", qns, codecItem.AcceptQn, selected_qn);
 
             if (selected_qn != DefaultQn)
@@ -373,7 +383,7 @@ namespace BililiveRecorder.Core.Recording
                     request.Headers.Host = originalUri.IsDefaultPort ? originalUri.Host : originalUri.Host + ":" + originalUri.Port;
                 }
 
-            sendRequest:
+sendRequest:
 
                 var resp = await client.SendAsync(request,
                      HttpCompletionOption.ResponseHeadersRead,
@@ -392,8 +402,8 @@ namespace BililiveRecorder.Core.Recording
                     case HttpStatusCode.Moved:
                     case HttpStatusCode.Redirect:
                         {
-                            fullUrl = new Uri(originalUri, resp.Headers.Location).ToString();
-                            this.logger.Debug("跳转到 {Url}, 原文本 {Location}", fullUrl, resp.Headers.Location.OriginalString);
+                            fullUrl = new Uri(originalUri, resp.Headers.Location!).ToString();
+                            this.logger.Debug("跳转到 {Url}, 原文本 {Location}", fullUrl, resp.Headers.Location!.OriginalString);
                             resp.Dispose();
                             streamHostInfoBuilder.Append('\n');
                             break;
diff --git a/BililiveRecorder.Core/Recording/StandardRecordTask.cs b/BililiveRecorder.Core/Recording/StandardRecordTask.cs
index 0343753..13f5b33 100644
--- a/BililiveRecorder.Core/Recording/StandardRecordTask.cs
+++ b/BililiveRecorder.Core/Recording/StandardRecordTask.cs
@@ -151,7 +151,11 @@ namespace BililiveRecorder.Core.Recording
             finally
             {
                 this.timer.Stop();
+#if NET6_0_OR_GREATER
+                await stream.DisposeAsync().ConfigureAwait(false);
+#else
                 stream.Dispose();
+#endif
                 await writer.CompleteAsync(exception).ConfigureAwait(false);
             }
         }
@@ -265,7 +269,7 @@ namespace BililiveRecorder.Core.Recording
             }
         }
 
-        private void StatsRule_StatsUpdated(object sender, RecordingStatsEventArgs e)
+        private void StatsRule_StatsUpdated(object? sender, RecordingStatsEventArgs e)
         {
             switch (this.room.RoomConfig.CuttingMode)
             {
@@ -300,7 +304,7 @@ namespace BililiveRecorder.Core.Recording
                 var paths = this.task.CreateFileName();
 
                 try
-                { _ = Directory.CreateDirectory(Path.GetDirectoryName(paths.fullPath)); }
+                { _ = Directory.CreateDirectory(Path.GetDirectoryName(paths.fullPath)!); }
                 catch (Exception) { }
 
                 this.last_path = paths.fullPath;
@@ -317,7 +321,7 @@ namespace BililiveRecorder.Core.Recording
                     : Path.ChangeExtension(this.last_path, "txt");
 
                 try
-                { _ = Directory.CreateDirectory(Path.GetDirectoryName(path)); }
+                { _ = Directory.CreateDirectory(Path.GetDirectoryName(path)!); }
                 catch (Exception) { }
 
                 var stream = new FileStream(path, FileMode.Append, FileAccess.Write, FileShare.Read);
diff --git a/BililiveRecorder.Core/Room.cs b/BililiveRecorder.Core/Room.cs
index f54de53..a5fb401 100644
--- a/BililiveRecorder.Core/Room.cs
+++ b/BililiveRecorder.Core/Room.cs
@@ -402,7 +402,7 @@ namespace BililiveRecorder.Core
         #region Event Handlers
 
         ///
-        private void RecordTask_IOStats(object sender, IOStatsEventArgs e)
+        private void RecordTask_IOStats(object? sender, IOStatsEventArgs e)
         {
             this.logger.Verbose("IO stats: {@stats}", e);
 
@@ -420,7 +420,7 @@ namespace BililiveRecorder.Core
         }
 
         ///
-        private void RecordTask_RecordingStats(object sender, RecordingStatsEventArgs e)
+        private void RecordTask_RecordingStats(object? sender, RecordingStatsEventArgs e)
         {
             this.logger.Verbose("Recording stats: {@stats}", e);
 
@@ -454,7 +454,7 @@ namespace BililiveRecorder.Core
         }
 
         ///
-        private void RecordTask_RecordFileClosed(object sender, RecordFileClosedEventArgs e)
+        private void RecordTask_RecordFileClosed(object? sender, RecordFileClosedEventArgs e)
         {
             this.basicDanmakuWriter.Disable();
 
@@ -462,7 +462,7 @@ namespace BililiveRecorder.Core
         }
 
         ///
-        private void RecordTask_RecordFileOpening(object sender, RecordFileOpeningEventArgs e)
+        private void RecordTask_RecordFileOpening(object? sender, RecordFileOpeningEventArgs e)
         {
             if (this.RoomConfig.RecordDanmaku)
                 this.basicDanmakuWriter.EnableWithPath(Path.ChangeExtension(e.FullPath, "xml"), this);
@@ -481,7 +481,7 @@ namespace BililiveRecorder.Core
         {
             const int MAX_ATTEMPT = 3;
             var attempt = 0;
-        retry:
+retry:
             try
             {
                 var coverUrl = this.RawBilibiliApiJsonData?["room_info"]?["cover"]?.ToObject<string>();
@@ -513,7 +513,7 @@ namespace BililiveRecorder.Core
         }
 
         ///
-        private void RecordTask_RecordSessionEnded(object sender, EventArgs e)
+        private void RecordTask_RecordSessionEnded(object? sender, EventArgs e)
         {
             Guid id;
             lock (this.recordStartLock)
@@ -570,7 +570,7 @@ namespace BililiveRecorder.Core
             return this.userScriptRunner.CallOnDanmakuHandshake(this.logger, this, json);
         }
 
-        private void DanmakuClient_DanmakuReceived(object sender, Api.Danmaku.DanmakuReceivedEventArgs e)
+        private void DanmakuClient_DanmakuReceived(object? sender, Api.Danmaku.DanmakuReceivedEventArgs e)
         {
             var d = e.Danmaku;
 
@@ -603,7 +603,7 @@ namespace BililiveRecorder.Core
             _ = Task.Run(async () => await this.basicDanmakuWriter.WriteAsync(d));
         }
 
-        private void DanmakuClient_StatusChanged(object sender, Api.Danmaku.StatusChangedEventArgs e)
+        private void DanmakuClient_StatusChanged(object? sender, Api.Danmaku.StatusChangedEventArgs e)
         {
             this.DanmakuConnected = e.Connected;
             if (e.Connected)
@@ -622,7 +622,7 @@ namespace BililiveRecorder.Core
             }
         }
 
-        private void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
+        private void Timer_Elapsed(object? sender, System.Timers.ElapsedEventArgs e)
         {
             this.StartDamakuConnection(delay: false);
 
@@ -645,7 +645,7 @@ namespace BililiveRecorder.Core
             }
         }
 
-        private void Room_PropertyChanged(object sender, PropertyChangedEventArgs e)
+        private void Room_PropertyChanged(object? sender, PropertyChangedEventArgs e)
         {
             switch (e.PropertyName)
             {
@@ -666,7 +666,7 @@ namespace BililiveRecorder.Core
             }
         }
 
-        private void RoomConfig_PropertyChanged(object sender, PropertyChangedEventArgs e)
+        private void RoomConfig_PropertyChanged(object? sender, PropertyChangedEventArgs e)
         {
             switch (e.PropertyName)
             {
diff --git a/BililiveRecorder.Core/Scripting/Runtime/JintURLSearchParams.cs b/BililiveRecorder.Core/Scripting/Runtime/JintURLSearchParams.cs
index 3e3bc90..5e204a4 100644
--- a/BililiveRecorder.Core/Scripting/Runtime/JintURLSearchParams.cs
+++ b/BililiveRecorder.Core/Scripting/Runtime/JintURLSearchParams.cs
@@ -43,9 +43,9 @@ namespace BililiveRecorder.Core.Scripting.Runtime
             this.query.Remove(name);
         }
 
-        public string[][] Entries()
+        public string?[][] Entries()
         {
-            return this.query.Select(x => new string[] { x.Name, x.Value.ToString() }).ToArray();
+            return this.query.Select(x => new string?[] { x.Name, x.Value.ToString() }).ToArray();
         }
 
         public void ForEach(FunctionInstance callback, JsValue thisArg)
@@ -63,7 +63,7 @@ namespace BililiveRecorder.Core.Scripting.Runtime
             return this.query.TryGetFirst(name, out var value) ? value.ToString() : null;
         }
 
-        public string[] GetAll(string name)
+        public string?[] GetAll(string name)
         {
             return this.query.GetAll(name).Select(x => x.ToString()).ToArray();
         }
@@ -93,7 +93,7 @@ namespace BililiveRecorder.Core.Scripting.Runtime
             return this.query.ToString();
         }
 
-        public string[] Values()
+        public string?[] Values()
         {
             return this.query.Select(x => x.Value.ToString()).ToArray();
         }
diff --git a/BililiveRecorder.Core/Templating/FileNameGenerator.cs b/BililiveRecorder.Core/Templating/FileNameGenerator.cs
index 331e98a..570f889 100644
--- a/BililiveRecorder.Core/Templating/FileNameGenerator.cs
+++ b/BililiveRecorder.Core/Templating/FileNameGenerator.cs
@@ -108,7 +108,7 @@ namespace BililiveRecorder.Core.Templating
             relativePath = template.Render(context);
             relativePath = RemoveInvalidFileName(relativePath);
 
-            fullPath = skipFullPath ? null : Path.GetFullPath(Path.Combine(workDirectory, relativePath));
+            fullPath = workDirectory is null ? null : Path.GetFullPath(Path.Combine(workDirectory, relativePath));
 
             if (!skipFullPath && !CheckIsWithinPath(workDirectory!, fullPath!))
             {
@@ -138,9 +138,9 @@ namespace BililiveRecorder.Core.Templating
 
             return new FileNameTemplateOutput(status, errorMessage, relativePath, fullPath);
 
-        returnDefaultPath:
+returnDefaultPath:
             var defaultRelativePath = RemoveInvalidFileName(defaultTemplate.Render(context));
-            var defaultFullPath = skipFullPath ? null : Path.GetFullPath(Path.Combine(workDirectory, defaultRelativePath));
+            var defaultFullPath = workDirectory is null ? null : Path.GetFullPath(Path.Combine(workDirectory, defaultRelativePath));
 
             return new FileNameTemplateOutput(status, errorMessage, defaultRelativePath, defaultFullPath);
         }
@@ -230,7 +230,7 @@ namespace BililiveRecorder.Core.Templating
         internal static string RemoveInvalidFileName(string input, bool ignore_slash = true)
         {
             foreach (var c in Path.GetInvalidFileNameChars())
-                if (!ignore_slash || c != '\\' && c != '/')
+                if (!ignore_slash || (c != '\\' && c != '/'))
                     input = input.Replace(c, '_');
 
             input = invalidDirectoryNameRegex.Replace(input, "$1_$2");
diff --git a/BililiveRecorder.WPF/Controls/RoomCard.xaml.cs b/BililiveRecorder.WPF/Controls/RoomCard.xaml.cs
index 04458a1..babc5e3 100644
--- a/BililiveRecorder.WPF/Controls/RoomCard.xaml.cs
+++ b/BililiveRecorder.WPF/Controls/RoomCard.xaml.cs
@@ -26,7 +26,9 @@ namespace BililiveRecorder.WPF.Controls
 
         private void MenuItem_StopRecording_Click(object sender, RoutedEventArgs e) => (this.DataContext as IRoom)?.StopRecord();
 
+#pragma warning disable VSTHRD110 // Observe result of async calls
         private void MenuItem_RefreshInfo_Click(object sender, RoutedEventArgs e) => (this.DataContext as IRoom)?.RefreshRoomInfoAsync();
+#pragma warning restore VSTHRD110 // Observe result of async calls
 
         private void MenuItem_StartMonitor_Click(object sender, RoutedEventArgs e)
         {
diff --git a/BililiveRecorder.WPF/SingleInstance.cs b/BililiveRecorder.WPF/SingleInstance.cs
index 14568ec..f550e62 100644
--- a/BililiveRecorder.WPF/SingleInstance.cs
+++ b/BililiveRecorder.WPF/SingleInstance.cs
@@ -68,7 +68,9 @@ namespace BililiveRecorder.WPF
 
         private class IPCRemoteService : MarshalByRefObject
         {
+#pragma warning disable VSTHRD110 // Observe result of async calls
             public void Notify() => Application.Current?.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)ActivateFirstInstanceCallback);
+#pragma warning restore VSTHRD110 // Observe result of async calls
             public override object? InitializeLifetimeService() => null;
         }
     }