diff --git a/src/SDKs/O2NG.Sdk.NetCore/O2NG.Sdk.NetCore.Models/O2NextGen.Sdk.NetCore.Models.csproj b/src/SDKs/O2NG.Sdk.NetCore/O2NG.Sdk.NetCore.Models/O2NextGen.Sdk.NetCore.Models.csproj
index 84a4445b..e3d50db2 100644
--- a/src/SDKs/O2NG.Sdk.NetCore/O2NG.Sdk.NetCore.Models/O2NextGen.Sdk.NetCore.Models.csproj
+++ b/src/SDKs/O2NG.Sdk.NetCore/O2NG.Sdk.NetCore.Models/O2NextGen.Sdk.NetCore.Models.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/IoC/ServiceCollectionExtensions.cs b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/IoC/ServiceCollectionExtensions.cs
index f20c0057..41739ca2 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/IoC/ServiceCollectionExtensions.cs
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/IoC/ServiceCollectionExtensions.cs
@@ -3,6 +3,8 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Newtonsoft.Json.Converters;
+using Newtonsoft.Json.Serialization;
 using O2NextGen.CertificateManagement.Api.Filters;
 using O2NextGen.CertificateManagement.Business.Services;
 using O2NextGen.CertificateManagement.Data;
@@ -32,10 +34,19 @@ public static IServiceCollection AddRequiredMvcComponents(this IServiceCollectio
         {
             services.AddTransient<ApiExceptionFilter>();
 
-            var mvcBuilder = services.AddMvcCore(options => { options.Filters.Add<ApiExceptionFilter>(); });
+            var mvcBuilder = services
+                .AddMvcCore(options =>
+                {
+                    options.Filters.Add<ApiExceptionFilter>();
+                });
+
             mvcBuilder.AddApiExplorer(); //for swagger
-            mvcBuilder.SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
-            mvcBuilder.AddJsonFormatters();
+            mvcBuilder.SetCompatibilityVersion(CompatibilityVersion.Version_3_0);
+            mvcBuilder.AddNewtonsoftJson(o =>
+            {
+                o.SerializerSettings.Converters.Add(new StringEnumConverter());
+                o.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
+            });
             return services;
         }
 
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/O2NextGen.CertificateManagement.Api.csproj b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/O2NextGen.CertificateManagement.Api.csproj
index ba989a7c..eab7d81a 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/O2NextGen.CertificateManagement.Api.csproj
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/O2NextGen.CertificateManagement.Api.csproj
@@ -1,13 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
     <UserSecretsId>e238f36a-3514-4436-b624-9b4f799bb82d</UserSecretsId>
     <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
     <DockerfileContext>..\..\..</DockerfileContext>
     <DockerComposeProjectPath>..\..\..\docker-compose.dcproj</DockerComposeProjectPath>
   </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(RunConfiguration)' == 'O2NextGen.CertificateManagement.Web' " />
   <ItemGroup>
     <Folder Include="wwwroot\" />
   </ItemGroup>
@@ -28,6 +29,7 @@
     <PackageReference Include="Serilog.Sinks.File" Version="2.2.0">
     </PackageReference>
     <PackageReference Include="Swashbuckle.AspNetCore" Version="4.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.31" />
   </ItemGroup>
 
   <ItemGroup>
@@ -56,6 +58,7 @@
 
   <ItemGroup>
     <None Remove="Logs\**" />
+    <None Remove="Microsoft.AspNetCore.Mvc.NewtonsoftJson" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Program.cs b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Program.cs
index 6294804b..cd8ff93b 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Program.cs
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Program.cs
@@ -18,7 +18,7 @@ public static async Task<int> Main(string[] args)
             
             try
             {
-                var host = CreateWebHostBuilder(args).Build();
+                var host = CreateHostBuilder(args);
                 Log.Information($"############### {AppName} ##############");
                 Log.Information("################# Starting Application #################");
                 await host.EnsureDbUpdate();
@@ -37,12 +37,13 @@ public static async Task<int> Main(string[] args)
             }
         }
 
-        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
+        public static IWebHost CreateHostBuilder(string[] args) =>
             WebHost.CreateDefaultBuilder(args)
                 .UseSerilog((context, configuration) =>
                 {
                     configuration.ReadFrom.Configuration(context.Configuration);
                 })
-                .UseStartup<Startup>(); // <- Add this line
+                .UseStartup<Startup>()
+                .Build(); 
     }
 }
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Startup.cs b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Startup.cs
index 91a4200e..615f3ad4 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Startup.cs
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Api/Startup.cs
@@ -86,7 +86,8 @@ public void Configure(IApplicationBuilder app, IHostingEnvironment env)
                 await next.Invoke();
             });
 
-            app.UseMvc();
+            app.UseRouting();
+            app.UseEndpoints(endpoints => { endpoints.MapControllers(); });
         }
     }
 }
\ No newline at end of file
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Business/O2NextGen.CertificateManagement.Business.csproj b/src/Services/c-gen/O2NextGen.CertificateManagement.Business/O2NextGen.CertificateManagement.Business.csproj
index 37c6e8da..71f19599 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Business/O2NextGen.CertificateManagement.Business.csproj
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Business/O2NextGen.CertificateManagement.Business.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Data/O2NextGen.CertificateManagement.Data.csproj b/src/Services/c-gen/O2NextGen.CertificateManagement.Data/O2NextGen.CertificateManagement.Data.csproj
index 68520b18..6ac5a3a7 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Data/O2NextGen.CertificateManagement.Data.csproj
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Data/O2NextGen.CertificateManagement.Data.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Services/c-gen/O2NextGen.CertificateManagement.Impl/O2NextGen.CertificateManagement.Impl.csproj b/src/Services/c-gen/O2NextGen.CertificateManagement.Impl/O2NextGen.CertificateManagement.Impl.csproj
index c29078c1..9ffe7a09 100644
--- a/src/Services/c-gen/O2NextGen.CertificateManagement.Impl/O2NextGen.CertificateManagement.Impl.csproj
+++ b/src/Services/c-gen/O2NextGen.CertificateManagement.Impl/O2NextGen.CertificateManagement.Impl.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/Services/c-gen/Tests/IntegrationTests.O2NextGen.CertificateManagement.Api/IntegrationTests.O2NextGen.CertificateManagement.Api.csproj b/src/Services/c-gen/Tests/IntegrationTests.O2NextGen.CertificateManagement.Api/IntegrationTests.O2NextGen.CertificateManagement.Api.csproj
index f00cd14e..797f72ff 100644
--- a/src/Services/c-gen/Tests/IntegrationTests.O2NextGen.CertificateManagement.Api/IntegrationTests.O2NextGen.CertificateManagement.Api.csproj
+++ b/src/Services/c-gen/Tests/IntegrationTests.O2NextGen.CertificateManagement.Api/IntegrationTests.O2NextGen.CertificateManagement.Api.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
diff --git a/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Api/Tests.O2NextGen.CertificateManagement.Api.csproj b/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Api/Tests.O2NextGen.CertificateManagement.Api.csproj
index 263a4732..21dbea45 100644
--- a/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Api/Tests.O2NextGen.CertificateManagement.Api.csproj
+++ b/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Api/Tests.O2NextGen.CertificateManagement.Api.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
diff --git a/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Impl/Tests.O2NextGen.CertificateManagement.Impl.csproj b/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Impl/Tests.O2NextGen.CertificateManagement.Impl.csproj
index 263a4732..21dbea45 100644
--- a/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Impl/Tests.O2NextGen.CertificateManagement.Impl.csproj
+++ b/src/Services/c-gen/Tests/Tests.O2NextGen.CertificateManagement.Impl/Tests.O2NextGen.CertificateManagement.Impl.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>