diff --git a/AuthorizationServer/AuthorizationServer.csproj b/AuthorizationServer/AuthorizationServer.csproj
index f26a38e..f46c213 100644
--- a/AuthorizationServer/AuthorizationServer.csproj
+++ b/AuthorizationServer/AuthorizationServer.csproj
@@ -1,7 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
     <ReleaseVersion>1.0</ReleaseVersion>
   </PropertyGroup>
 
@@ -17,13 +19,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.9" />
-    <PackageReference Include="Microsoft.AspNetCore.Mvc.WebApiCompatShim" Version="2.0.1" />
-    <PackageReference Include="Authlete.Authlete" Version="1.4.0" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
+    <PackageReference Include="Authlete.Authlete" Version="1.5.0" />
   </ItemGroup>
 
 </Project>
diff --git a/AuthorizationServer/Startup.cs b/AuthorizationServer/Startup.cs
index 22ba409..3d70917 100644
--- a/AuthorizationServer/Startup.cs
+++ b/AuthorizationServer/Startup.cs
@@ -20,6 +20,7 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 using Authlete.Api;
 using Authlete.Conf;
 
@@ -42,7 +43,7 @@ public void ConfigureServices(IServiceCollection services)
             // AddWebApiConventions() is added by WebApiCompatShim.
             // Calling the method enables Web API implementations
             // to return an HttpResponseMessage instance directly.
-            services.AddMvc().AddWebApiConventions();
+            services.AddControllers();
 
             // Register an instance of IAuthleteApi so controllers
             // can refer to it in order to call Authlete Web APIs.
@@ -57,7 +58,7 @@ public void ConfigureServices(IServiceCollection services)
         }
 
 
-        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
+        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
         {
             if (env.IsDevelopment())
             {
@@ -66,7 +67,16 @@ public void Configure(IApplicationBuilder app, IHostingEnvironment env)
 
             app.UseDefaultFiles();
             app.UseStaticFiles();
-            app.UseMvc();
+            
+            // Updated to use routing
+            app.UseRouting();
+
+            // Configure endpoints for controllers
+            app.UseEndpoints(endpoints => 
+            {
+                // Ensure this matches your app's routing needs
+                endpoints.MapControllers(); 
+            });
         }