diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractCSharpCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractCSharpCodegen.java
index 78b5560d53d..ea396618db9 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractCSharpCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/AbstractCSharpCodegen.java
@@ -276,14 +276,15 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
     @Override
     public String toOperationId(String operationId) {
-        // throw exception if method name is empty
+        // throw exception if method name is empty (should not occur as an auto-generated method name will be used)
         if (StringUtils.isEmpty(operationId)) {
             throw new RuntimeException("Empty method name (operationId) not allowed");
         }
 
         // method name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(operationId)) {
-            throw new RuntimeException(operationId + " (reserved word) cannot be used as method name");
+            LOGGER.warn(operationId + " (reserved word) cannot be used as method name. Renamed to " + camelize(sanitizeName("call_" + operationId)));
+            operationId = "call_" + operationId;
         }
 
         return camelize(sanitizeName(operationId));
@@ -471,7 +472,8 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
 
         // model name cannot use reserved keyword, e.g. return
         if (reservedWords.contains(name)) {
-            throw new RuntimeException(name + " (reserved word) cannot be used as a model name");
+            LOGGER.warn(name + " (reserved word) cannot be used as model name. Renamed to " + camelize("object_" + name));
+            name = "object_" + name; // e.g. return => ObjectReturn (after camelize)
         }
 
         // camelize the model name
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient.Test/PetApiTests.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient.Test/PetApiTests.cs
index a7caec2f54c..7e3566eb04b 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient.Test/PetApiTests.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient.Test/PetApiTests.cs
@@ -156,15 +156,15 @@ namespace IO.Swagger.Test
         }
         
         /// <summary>
-        /// Test GetPetByIdWithByteArray
+        /// Test PetPetIdtestingByteArraytrueGet
         /// </summary>
         [Test]
-        public void GetPetByIdWithByteArrayTest()
+        public void PetPetIdtestingByteArraytrueGetTest()
         {
-            // TODO: add unit test for the method 'GetPetByIdWithByteArray'
+            // TODO: add unit test for the method 'PetPetIdtestingByteArraytrueGet'
             long? petId = null; // TODO: replace null with proper value
             
-            var response = instance.GetPetByIdWithByteArray(petId);
+            var response = instance.PetPetIdtestingByteArraytrueGet(petId);
             Assert.IsInstanceOf<byte[]> (response, "response is byte[]"); 
         }
         
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
index 5ef6e286a8d..2b44e177625 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/Lib/SwaggerClient/src/main/csharp/IO/Swagger/Api/PetApi.cs
@@ -212,7 +212,7 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>byte[]</returns>
-        byte[] GetPetByIdWithByteArray (long? petId);
+        byte[] PetPetIdtestingByteArraytrueGet (long? petId);
   
         /// <summary>
         /// Fake endpoint to test byte array return by &#39;Find pet by ID&#39;
@@ -223,7 +223,7 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>ApiResponse of byte[]</returns>
-        ApiResponse<byte[]> GetPetByIdWithByteArrayWithHttpInfo (long? petId);
+        ApiResponse<byte[]> PetPetIdtestingByteArraytrueGetWithHttpInfo (long? petId);
         
         /// <summary>
         /// Fake endpoint to test byte array in body parameter for adding a new pet to the store
@@ -446,7 +446,7 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>Task of byte[]</returns>
-        System.Threading.Tasks.Task<byte[]> GetPetByIdWithByteArrayAsync (long? petId);
+        System.Threading.Tasks.Task<byte[]> PetPetIdtestingByteArraytrueGetAsync (long? petId);
 
         /// <summary>
         /// Fake endpoint to test byte array return by &#39;Find pet by ID&#39;
@@ -457,7 +457,7 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>Task of ApiResponse (byte[])</returns>
-        System.Threading.Tasks.Task<ApiResponse<byte[]>> GetPetByIdWithByteArrayAsyncWithHttpInfo (long? petId);
+        System.Threading.Tasks.Task<ApiResponse<byte[]>> PetPetIdtestingByteArraytrueGetAsyncWithHttpInfo (long? petId);
         
         /// <summary>
         /// Fake endpoint to test byte array in body parameter for adding a new pet to the store
@@ -1972,9 +1972,9 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param> 
         /// <returns>byte[]</returns>
-        public byte[] GetPetByIdWithByteArray (long? petId)
+        public byte[] PetPetIdtestingByteArraytrueGet (long? petId)
         {
-             ApiResponse<byte[]> response = GetPetByIdWithByteArrayWithHttpInfo(petId);
+             ApiResponse<byte[]> response = PetPetIdtestingByteArraytrueGetWithHttpInfo(petId);
              return response.Data;
         }
 
@@ -1984,12 +1984,12 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param> 
         /// <returns>ApiResponse of byte[]</returns>
-        public ApiResponse< byte[] > GetPetByIdWithByteArrayWithHttpInfo (long? petId)
+        public ApiResponse< byte[] > PetPetIdtestingByteArraytrueGetWithHttpInfo (long? petId)
         {
             
             // verify the required parameter 'petId' is set
             if (petId == null)
-                throw new ApiException(400, "Missing required parameter 'petId' when calling PetApi->GetPetByIdWithByteArray");
+                throw new ApiException(400, "Missing required parameter 'petId' when calling PetApi->PetPetIdtestingByteArraytrueGet");
             
     
             var path_ = "/pet/{petId}?testing_byte_array=true";
@@ -2048,9 +2048,9 @@ namespace IO.Swagger.Api
             int statusCode = (int) response.StatusCode;
     
             if (statusCode >= 400)
-                throw new ApiException (statusCode, "Error calling GetPetByIdWithByteArray: " + response.Content, response.Content);
+                throw new ApiException (statusCode, "Error calling PetPetIdtestingByteArraytrueGet: " + response.Content, response.Content);
             else if (statusCode == 0)
-                throw new ApiException (statusCode, "Error calling GetPetByIdWithByteArray: " + response.ErrorMessage, response.ErrorMessage);
+                throw new ApiException (statusCode, "Error calling PetPetIdtestingByteArraytrueGet: " + response.ErrorMessage, response.ErrorMessage);
     
             return new ApiResponse<byte[]>(statusCode,
                 response.Headers.ToDictionary(x => x.Name, x => x.Value.ToString()),
@@ -2065,9 +2065,9 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>Task of byte[]</returns>
-        public async System.Threading.Tasks.Task<byte[]> GetPetByIdWithByteArrayAsync (long? petId)
+        public async System.Threading.Tasks.Task<byte[]> PetPetIdtestingByteArraytrueGetAsync (long? petId)
         {
-             ApiResponse<byte[]> response = await GetPetByIdWithByteArrayAsyncWithHttpInfo(petId);
+             ApiResponse<byte[]> response = await PetPetIdtestingByteArraytrueGetAsyncWithHttpInfo(petId);
              return response.Data;
 
         }
@@ -2078,10 +2078,10 @@ namespace IO.Swagger.Api
         /// <exception cref="IO.Swagger.Client.ApiException">Thrown when fails to make API call</exception>
         /// <param name="petId">ID of pet that needs to be fetched</param>
         /// <returns>Task of ApiResponse (byte[])</returns>
-        public async System.Threading.Tasks.Task<ApiResponse<byte[]>> GetPetByIdWithByteArrayAsyncWithHttpInfo (long? petId)
+        public async System.Threading.Tasks.Task<ApiResponse<byte[]>> PetPetIdtestingByteArraytrueGetAsyncWithHttpInfo (long? petId)
         {
             // verify the required parameter 'petId' is set
-            if (petId == null) throw new ApiException(400, "Missing required parameter 'petId' when calling GetPetByIdWithByteArray");
+            if (petId == null) throw new ApiException(400, "Missing required parameter 'petId' when calling PetPetIdtestingByteArraytrueGet");
             
     
             var path_ = "/pet/{petId}?testing_byte_array=true";
@@ -2142,9 +2142,9 @@ namespace IO.Swagger.Api
             int statusCode = (int) response.StatusCode;
  
             if (statusCode >= 400)
-                throw new ApiException (statusCode, "Error calling GetPetByIdWithByteArray: " + response.Content, response.Content);
+                throw new ApiException (statusCode, "Error calling PetPetIdtestingByteArraytrueGet: " + response.Content, response.Content);
             else if (statusCode == 0)
-                throw new ApiException (statusCode, "Error calling GetPetByIdWithByteArray: " + response.ErrorMessage, response.ErrorMessage);
+                throw new ApiException (statusCode, "Error calling PetPetIdtestingByteArraytrueGet: " + response.ErrorMessage, response.ErrorMessage);
 
             return new ApiResponse<byte[]>(statusCode,
                 response.Headers.ToDictionary(x => x.Name, x => x.Value.ToString()),
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/SwaggerClientTest.userprefs b/samples/client/petstore/csharp/SwaggerClientTest/SwaggerClientTest.userprefs
index 98bc9083d66..23716351001 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/SwaggerClientTest.userprefs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/SwaggerClientTest.userprefs
@@ -1,8 +1,8 @@
 <Properties StartupItem="SwaggerClientTest.csproj">
   <MonoDevelop.Ide.Workspace ActiveConfiguration="Debug" />
-  <MonoDevelop.Ide.Workbench ActiveDocument="TestOrder.cs">
+  <MonoDevelop.Ide.Workbench ActiveDocument="TestPet.cs">
     <Files>
-      <File FileName="TestPet.cs" Line="84" Column="10" />
+      <File FileName="TestPet.cs" Line="162" Column="35" />
       <File FileName="TestOrder.cs" Line="42" Column="12" />
     </Files>
   </MonoDevelop.Ide.Workbench>
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/TestPet.cs b/samples/client/petstore/csharp/SwaggerClientTest/TestPet.cs
index 640d24250d9..24934702118 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/TestPet.cs
+++ b/samples/client/petstore/csharp/SwaggerClientTest/TestPet.cs
@@ -168,7 +168,7 @@ namespace SwaggerClientTest.TestPet
 			Configuration c1 = new Configuration (timeout: 10000);
 
 			PetApi petApi = new PetApi (c1);
-			byte[] response = petApi.GetPetByIdWithByteArray (petId);
+			byte[] response = petApi.PetPetIdtestingByteArraytrueGet (petId);
 			Assert.IsInstanceOf<byte[]> (response, "Response is byte array");
 		}
 
diff --git a/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.csproj.FilesWrittenAbsolute.txt b/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.csproj.FilesWrittenAbsolute.txt
index f115c595d6a..323cad108c6 100644
--- a/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.csproj.FilesWrittenAbsolute.txt
+++ b/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.csproj.FilesWrittenAbsolute.txt
@@ -1,9 +1,9 @@
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/.NETFramework,Version=v4.5.AssemblyAttribute.cs
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.swagger-logo.png
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/Newtonsoft.Json.dll
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/nunit.framework.dll
-/Users/williamcheng/Code/wing328/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/RestSharp.dll
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/.NETFramework,Version=v4.5.AssemblyAttribute.cs
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.swagger-logo.png
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll.mdb
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/SwaggerClientTest.dll
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/obj/Debug/SwaggerClientTest.dll.mdb
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/Newtonsoft.Json.dll
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/nunit.framework.dll
+/Users/williamcheng/Code/swagger-codegen/samples/client/petstore/csharp/SwaggerClientTest/bin/Debug/RestSharp.dll