diff --git a/Shadowsocks.WPF/Services/Sip003Plugin.cs b/Shadowsocks.WPF/Services/Sip003Plugin.cs
index c57f6127..652b2fca 100644
--- a/Shadowsocks.WPF/Services/Sip003Plugin.cs
+++ b/Shadowsocks.WPF/Services/Sip003Plugin.cs
@@ -41,7 +41,7 @@ namespace Shadowsocks.WPF.Services
                 showPluginOutput);
         }
 
-        private Sip003Plugin(string plugin, string pluginOpts, List<string> pluginArgs, string serverAddress, int serverPort, bool showPluginOutput)
+        private Sip003Plugin(string plugin, string? pluginOpts, List<string>? pluginArgs, string serverAddress, int serverPort, bool showPluginOutput)
         {
             if (plugin == null) throw new ArgumentNullException(nameof(plugin));
             if (string.IsNullOrWhiteSpace(serverAddress))
@@ -50,7 +50,7 @@ namespace Shadowsocks.WPF.Services
             }
             if (serverPort <= 0 || serverPort > 65535)
             {
-                throw new ArgumentOutOfRangeException("serverPort");
+                throw new ArgumentOutOfRangeException(nameof(serverPort));
             }
 
             var pluginProcessStartInfo = new ProcessStartInfo
@@ -68,8 +68,9 @@ namespace Shadowsocks.WPF.Services
                         ["SS_PLUGIN_OPTIONS"] = pluginOpts
                     }
             };
-            foreach (var arg in pluginArgs)
-                pluginProcessStartInfo.ArgumentList.Add(arg);
+            if (pluginArgs != null)
+                foreach (var arg in pluginArgs)
+                    pluginProcessStartInfo.ArgumentList.Add(arg);
 
             _pluginProcess = new Process()
             {
@@ -119,7 +120,7 @@ namespace Shadowsocks.WPF.Services
             return true;
         }
 
-        public string ExpandEnvironmentVariables(string name, StringDictionary? environmentVariables = null)
+        public static string ExpandEnvironmentVariables(string name, StringDictionary? environmentVariables = null)
         {
             // Expand the environment variables from the new process itself
             if (environmentVariables != null)
@@ -134,11 +135,11 @@ namespace Shadowsocks.WPF.Services
             return name;
         }
 
-        static int GetNextFreeTcpPort()
+        public static int GetNextFreeTcpPort()
         {
             var l = new TcpListener(IPAddress.Loopback, 0);
             l.Start();
-            int port = ((IPEndPoint)l.LocalEndpoint).Port;
+            var port = ((IPEndPoint)l.LocalEndpoint).Port;
             l.Stop();
             return port;
         }
diff --git a/Shadowsocks/Models/Group.cs b/Shadowsocks/Models/Group.cs
index ad817d28..50b09265 100644
--- a/Shadowsocks/Models/Group.cs
+++ b/Shadowsocks/Models/Group.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Text;
 using System.Text.Json.Serialization;
 
 namespace Shadowsocks.Models
@@ -27,12 +26,14 @@ namespace Shadowsocks.Models
         /// Gets or sets the data usage in bytes.
         /// The value is fetched from SIP008 provider.
         /// </summary>
+        [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
         public ulong BytesUsed { get; set; }
 
         /// <summary>
         /// Gets or sets the data remaining to be used in bytes.
         /// The value is fetched from SIP008 provider.
         /// </summary>
+        [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
         public ulong BytesRemaining { get; set; }
 
         public Group() : this(string.Empty)
diff --git a/Shadowsocks/Models/IServer.cs b/Shadowsocks/Models/IServer.cs
index 82cdcf9f..2b232e0a 100644
--- a/Shadowsocks/Models/IServer.cs
+++ b/Shadowsocks/Models/IServer.cs
@@ -31,13 +31,13 @@ namespace Shadowsocks.Models
         /// Gets or sets the plugin executable filename.
         /// </summary>
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
-        public string Plugin { get; set; }
+        public string? Plugin { get; set; }
 
         /// <summary>
         /// Gets or sets the plugin options passed as environment variables.
         /// </summary>
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
-        public string PluginOpts { get; set; }
+        public string? PluginOpts { get; set; }
 
         /// <summary>
         /// Gets or sets the server name.
diff --git a/Shadowsocks/Models/Server.cs b/Shadowsocks/Models/Server.cs
index 6f9c276c..34f64e31 100644
--- a/Shadowsocks/Models/Server.cs
+++ b/Shadowsocks/Models/Server.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Text;
 using System.Text.Json.Serialization;
 
 namespace Shadowsocks.Models
@@ -23,17 +22,17 @@ namespace Shadowsocks.Models
 
         /// <inheritdoc/>
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
-        public string Plugin { get; set; }
+        public string? Plugin { get; set; }
 
         /// <inheritdoc/>
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
-        public string PluginOpts { get; set; }
+        public string? PluginOpts { get; set; }
 
         /// <summary>
         /// Gets or sets the arguments passed to the plugin process.
         /// </summary>
         [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingDefault)]
-        public List<string> PluginArgs { get; set; }
+        public List<string>? PluginArgs { get; set; }
 
         /// <inheritdoc/>
         [JsonPropertyName("remarks")]
@@ -49,9 +48,6 @@ namespace Shadowsocks.Models
             Port = 8388;
             Password = "";
             Method = "chacha20-ietf-poly1305";
-            Plugin = "";
-            PluginOpts = "";
-            PluginArgs = new();
             Name = "";
             Uuid = "";
         }
@@ -66,7 +62,7 @@ namespace Shadowsocks.Models
         /// <returns></returns>
         public Uri ToUrl()
         {
-            UriBuilder uriBuilder = new UriBuilder("ss", Host, Port)
+            UriBuilder uriBuilder = new("ss", Host, Port)
             {
                 UserName = Utilities.Base64Url.Encode($"{Method}:{Password}"),
                 Fragment = Name,
@@ -99,17 +95,20 @@ namespace Shadowsocks.Models
                 var userinfoSplitArray = userinfo.Split(':', 2);
                 var method = userinfoSplitArray[0];
                 var password = userinfoSplitArray[1];
+                var host = uri.HostNameType == UriHostNameType.IPv6 ? uri.Host[1..^1] : uri.Host;
+                var escapedFragment = string.IsNullOrEmpty(uri.Fragment) ? uri.Fragment : uri.Fragment[1..];
+                var name = Uri.UnescapeDataString(escapedFragment);
                 server = new Server()
                 {
-                    Name = uri.Fragment,
+                    Name = name,
                     Uuid = new Guid().ToString(),
-                    Host = uri.Host,
+                    Host = host,
                     Port = uri.Port,
                     Password = password,
                     Method = method,
                 };
                 // find the plugin query
-                var parsedQueriesArray = uri.Query.Split("?&");
+                var parsedQueriesArray = uri.Query.Split('?', '&');
                 var pluginQueryContent = "";
                 foreach (var query in parsedQueriesArray)
                 {
@@ -118,9 +117,15 @@ namespace Shadowsocks.Models
                         pluginQueryContent = query[7..]; // remove "plugin="
                     }
                 }
+                if (string.IsNullOrEmpty(pluginQueryContent)) // no plugin
+                    return true;
                 var unescapedpluginQuery = Uri.UnescapeDataString(pluginQueryContent);
                 var parsedPluginQueryArray = unescapedpluginQuery.Split(';', 2);
-                if (parsedPluginQueryArray.Length == 2) // is valid plugin query
+                if (parsedPluginQueryArray.Length == 1)
+                {
+                    server.Plugin = parsedPluginQueryArray[0];
+                }
+                else if (parsedPluginQueryArray.Length == 2) // is valid plugin query
                 {
                     server.Plugin = parsedPluginQueryArray[0];
                     server.PluginOpts = parsedPluginQueryArray[1];
@@ -129,7 +134,7 @@ namespace Shadowsocks.Models
             }
             catch
             {
-                server = new Server();
+                server = new();
                 return false;
             }
         }
diff --git a/Shadowsocks/Utilities/Base64Url.cs b/Shadowsocks/Utilities/Base64Url.cs
index 16b993ac..207c4efb 100644
--- a/Shadowsocks/Utilities/Base64Url.cs
+++ b/Shadowsocks/Utilities/Base64Url.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Text;
 
 namespace Shadowsocks.Utilities
@@ -14,7 +13,7 @@ namespace Shadowsocks.Utilities
 
         public static byte[] DecodeToBytes(string base64url)
         {
-            string base64string = base64url.Replace('_', '/').Replace('-', '+');
+            var base64string = base64url.Replace('_', '/').Replace('-', '+');
             base64string = base64string.PadRight(base64string.Length + (4 - base64string.Length % 4) % 4, '=');
             return Convert.FromBase64String(base64string);
         }