diff --git a/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache b/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
index 3105952c247..97b855dc534 100644
--- a/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
@@ -133,16 +133,18 @@ namespace {{packageName}}.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c362a4f5051..f3d8d64b477 100644
--- a/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/httpclient/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/httpclient/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.7/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/net4.8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c362a4f5051..f3d8d64b477 100644
--- a/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c362a4f5051..f3d8d64b477 100644
--- a/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/net8/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c362a4f5051..f3d8d64b477 100644
--- a/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/net9/EnumMappings/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/restsharp/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c362a4f5051..f3d8d64b477 100644
--- a/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/net9/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)
diff --git a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index c370847420c..6973f2bf669 100644
--- a/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/unityWebRequest/standard2.0/Petstore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -141,16 +141,18 @@ namespace Org.OpenAPITools.Client
             foreach (var parameter in requestOptions.QueryParameters)
             {
 #if (NETCOREAPP)
+                string framework = RuntimeInformation.FrameworkDescription;
+                string key = framework.StartsWith(".NET 9")?parameter.Key:HttpUtility.UrlEncode(parameter.Key);
                 if (parameter.Value.Count > 1)
                 { // array
                     foreach (var value in parameter.Value)
                     {
-                        httpValues.Add(HttpUtility.UrlEncode(parameter.Key) + "[]", value);
+                        httpValues.Add(key + "[]", value);
                     }
                 }
                 else
                 {
-                    httpValues.Add(HttpUtility.UrlEncode(parameter.Key), parameter.Value[0]);
+                    httpValues.Add(key, parameter.Value[0]);
                 }
 #else
                 if (parameter.Value.Count > 1)