diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/ApiClient.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/ApiClient.mustache
index 9d177d2c40e9..3e21a800e08e 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/ApiClient.mustache
@@ -317,7 +317,7 @@ namespace {{packageName}}.Client
                     request.RequestFormat = DataFormat.Json;
                 }
 
-                request.AddBody(options.Data);
+                request.AddJsonBody(options.Data);
             }
 
             if (options.FileParameters != null)
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/Configuration.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/Configuration.mustache
index f9a29c90aa33..90d09845bd49 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/Configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/Configuration.mustache
@@ -400,7 +400,7 @@ namespace {{packageName}}.Client
             {
                 ApiKey = apiKey,
                 ApiKeyPrefix = apiKeyPrefix,
-                DefaultHeader = defaultHeaders,
+                DefaultHeaders = defaultHeaders,
                 BasePath = second.BasePath ?? first.BasePath,
                 Timeout = second.Timeout,
                 UserAgent = second.UserAgent ?? first.UserAgent,
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/ApiClient.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/ApiClient.cs
index af5165ee251c..f500f1e5b9e2 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/ApiClient.cs
@@ -320,7 +320,7 @@ private RestRequest newRequest(
                     request.RequestFormat = DataFormat.Json;
                 }
 
-                request.AddBody(options.Data);
+                request.AddJsonBody(options.Data);
             }
 
             if (options.FileParameters != null)
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/Configuration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/Configuration.cs
index 9fadf1712f3b..177363611d67 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/Configuration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/Configuration.cs
@@ -395,7 +395,7 @@ public static IReadableConfiguration MergeConfigurations(IReadableConfiguration
             {
                 ApiKey = apiKey,
                 ApiKeyPrefix = apiKeyPrefix,
-                DefaultHeader = defaultHeaders,
+                DefaultHeaders = defaultHeaders,
                 BasePath = second.BasePath ?? first.BasePath,
                 Timeout = second.Timeout,
                 UserAgent = second.UserAgent ?? first.UserAgent,
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/ApiClient.cs b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/ApiClient.cs
index 05c50bceac02..12d3d49f7386 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/ApiClient.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/ApiClient.cs
@@ -321,7 +321,7 @@ private RestRequest newRequest(
                     request.RequestFormat = DataFormat.Json;
                 }
 
-                request.AddBody(options.Data);
+                request.AddJsonBody(options.Data);
             }
 
             if (options.FileParameters != null)
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/Configuration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/Configuration.cs
index 4317d59a9394..4c0720e504ad 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/Configuration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/Configuration.cs
@@ -400,7 +400,7 @@ public static IReadableConfiguration MergeConfigurations(IReadableConfiguration
             {
                 ApiKey = apiKey,
                 ApiKeyPrefix = apiKeyPrefix,
-                DefaultHeader = defaultHeaders,
+                DefaultHeaders = defaultHeaders,
                 BasePath = second.BasePath ?? first.BasePath,
                 Timeout = second.Timeout,
                 UserAgent = second.UserAgent ?? first.UserAgent,