diff --git a/.appveyor.yml b/.appveyor.yml
index 2f422dcb..5475bca7 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,5 +1,5 @@
 # Specify version format
-version: "5.0.11.{build}"
+version: "5.0.12.{build}"
 
 # Image to use
 image: Visual Studio 2019
diff --git a/examples/HttpServer/Program.cs b/examples/HttpServer/Program.cs
index aba310b0..279dcbb6 100644
--- a/examples/HttpServer/Program.cs
+++ b/examples/HttpServer/Program.cs
@@ -83,7 +83,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Required cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Required cache value was not found for the key: " + key));
             }
             else if ((request.Method == "POST") || (request.Method == "PUT"))
             {
@@ -117,7 +117,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Deleted cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Deleted cache value was not found for the key: " + key));
             }
             else if (request.Method == "OPTIONS")
                 SendResponseAsync(Response.MakeOptionsResponse());
diff --git a/examples/HttpsServer/Program.cs b/examples/HttpsServer/Program.cs
index 250d40c1..88e713d8 100644
--- a/examples/HttpsServer/Program.cs
+++ b/examples/HttpsServer/Program.cs
@@ -85,7 +85,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Required cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Required cache value was not found for the key: " + key));
             }
             else if ((request.Method == "POST") || (request.Method == "PUT"))
             {
@@ -119,7 +119,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Deleted cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Deleted cache value was not found for the key: " + key));
             }
             else if (request.Method == "OPTIONS")
                 SendResponseAsync(Response.MakeOptionsResponse());
diff --git a/source/NetCoreServer/HttpResponse.cs b/source/NetCoreServer/HttpResponse.cs
index 905b92bf..a2e3719a 100644
--- a/source/NetCoreServer/HttpResponse.cs
+++ b/source/NetCoreServer/HttpResponse.cs
@@ -565,13 +565,26 @@ public HttpResponse MakeOkResponse(int status = 200)
         /// <summary>
         /// Make ERROR response
         /// </summary>
-        /// <param name="error">Error content (default is "")</param>
-        /// <param name="status">OK status (default is 200 (OK))</param>
-        public HttpResponse MakeErrorResponse(string error = "", int status = 500)
+        /// <param name="content">Error content (default is "")</param>
+        /// <param name="contentType">Error content type (default is "text/plain; charset=UTF-8")</param>
+        public HttpResponse MakeErrorResponse(string content = "", string contentType = "text/plain; charset=UTF-8")
+        {
+            return MakeErrorResponse(500, content, contentType);
+        }
+
+        /// <summary>
+        /// Make ERROR response
+        /// </summary>
+        /// <param name="status">Error status</param>
+        /// <param name="content">Error content (default is "")</param>
+        /// <param name="contentType">Error content type (default is "text/plain; charset=UTF-8")</param>
+        public HttpResponse MakeErrorResponse(int status, string content = "", string contentType = "text/plain; charset=UTF-8")
         {
             Clear();
             SetBegin(status);
-            SetBody(error);
+            if (!string.IsNullOrEmpty(contentType))
+                SetHeader("Content-Type", contentType);
+            SetBody(content);
             return this;
         }
 
@@ -589,7 +602,7 @@ public HttpResponse MakeHeadResponse()
         /// <summary>
         /// Make GET response
         /// </summary>
-        /// <param name="content">String content</param>
+        /// <param name="content">String content (default is "")</param>
         /// <param name="contentType">Content type (default is "text/plain; charset=UTF-8")</param>
         public HttpResponse MakeGetResponse(string content = "", string contentType = "text/plain; charset=UTF-8")
         {
@@ -900,7 +913,7 @@ internal bool ReceiveBody(byte[] buffer, int offset, int size)
                     return true;
                 }
             }
-            else 
+            else
             {
                 // Check the body content to find the response body end
                 if (_bodySize >= 4)
diff --git a/source/NetCoreServer/NetCoreServer.csproj b/source/NetCoreServer/NetCoreServer.csproj
index cc2f918f..910b93fe 100644
--- a/source/NetCoreServer/NetCoreServer.csproj
+++ b/source/NetCoreServer/NetCoreServer.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net5.0</TargetFramework>
-    <Version>5.0.11.0</Version>
+    <Version>5.0.12.0</Version>
     <Authors>Ivan Shynkarenka</Authors>
     <Copyright>Copyright (c) 2019-2021 Ivan Shynkarenka</Copyright>
     <RepositoryUrl>https://github.com/chronoxor/NetCoreServer</RepositoryUrl>
diff --git a/source/NetCoreServer/WebSocket.cs b/source/NetCoreServer/WebSocket.cs
index 7fe83384..ad7b9967 100644
--- a/source/NetCoreServer/WebSocket.cs
+++ b/source/NetCoreServer/WebSocket.cs
@@ -156,7 +156,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
                     if ((string.Compare(value, "Upgrade", StringComparison.OrdinalIgnoreCase) != 0) && (string.Compare(value, "keep-alive, Upgrade", StringComparison.OrdinalIgnoreCase) != 0))
                     {
                         error = true;
-                        response.MakeErrorResponse("Invalid WebSocket handshaked request: 'Connection' header value must be 'Upgrade' or 'keep-alive, Upgrade'", 400);
+                        response.MakeErrorResponse(400, "Invalid WebSocket handshaked request: 'Connection' header value must be 'Upgrade' or 'keep-alive, Upgrade'");
                         break;
                     }
 
@@ -167,7 +167,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
                     if (string.Compare(value, "websocket", StringComparison.OrdinalIgnoreCase) != 0)
                     {
                         error = true;
-                        response.MakeErrorResponse("Invalid WebSocket handshaked request: 'Upgrade' header value must be 'websocket'", 400);
+                        response.MakeErrorResponse(400, "Invalid WebSocket handshaked request: 'Upgrade' header value must be 'websocket'");
                         break;
                     }
 
@@ -178,7 +178,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
                     if (string.IsNullOrEmpty(value))
                     {
                         error = true;
-                        response.MakeErrorResponse("Invalid WebSocket handshaked request: 'Sec-WebSocket-Key' header value must be non empty", 400);
+                        response.MakeErrorResponse(400, "Invalid WebSocket handshaked request: 'Sec-WebSocket-Key' header value must be non empty");
                         break;
                     }
 
@@ -199,7 +199,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
                     if (string.Compare(value, "13", StringComparison.OrdinalIgnoreCase) != 0)
                     {
                         error = true;
-                        response.MakeErrorResponse("Invalid WebSocket handshaked request: 'Sec-WebSocket-Version' header value must be '13'", 400);
+                        response.MakeErrorResponse(400, "Invalid WebSocket handshaked request: 'Sec-WebSocket-Version' header value must be '13'");
                         break;
                     }
 
@@ -215,7 +215,7 @@ public bool PerformServerUpgrade(HttpRequest request, HttpResponse response)
             if (!connection || !upgrade || !wsKey || !wsVersion)
             {
                 if (!error)
-                    response.MakeErrorResponse("Invalid WebSocket response", 400);
+                    response.MakeErrorResponse(400, "Invalid WebSocket response");
                 _wsHandler.SendUpgrade(response);
                 return false;
             }
diff --git a/tests/HttpTests.cs b/tests/HttpTests.cs
index 90806afe..ed97aaab 100644
--- a/tests/HttpTests.cs
+++ b/tests/HttpTests.cs
@@ -82,7 +82,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Required cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Required cache value was not found for the key: " + key));
             }
             else if ((request.Method == "POST") || (request.Method == "PUT"))
             {
@@ -116,7 +116,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Deleted cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Deleted cache value was not found for the key: " + key));
             }
             else if (request.Method == "OPTIONS")
                 SendResponseAsync(Response.MakeOptionsResponse());
diff --git a/tests/HttpsTests.cs b/tests/HttpsTests.cs
index 1be8a724..c78b6d3c 100644
--- a/tests/HttpsTests.cs
+++ b/tests/HttpsTests.cs
@@ -39,7 +39,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Required cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Required cache value was not found for the key: " + key));
             }
             else if ((request.Method == "POST") || (request.Method == "PUT"))
             {
@@ -73,7 +73,7 @@ protected override void OnReceivedRequest(HttpRequest request)
                     SendResponseAsync(Response.MakeGetResponse(value));
                 }
                 else
-                    SendResponseAsync(Response.MakeErrorResponse("Deleted cache value was not found for the key: " + key, 404));
+                    SendResponseAsync(Response.MakeErrorResponse(404, "Deleted cache value was not found for the key: " + key));
             }
             else if (request.Method == "OPTIONS")
                 SendResponseAsync(Response.MakeOptionsResponse());