diff --git a/framework/src/Volo.Abp.Swashbuckle/Microsoft/AspNetCore/Builder/AbpSwaggerUIBuilderExtensions.cs b/framework/src/Volo.Abp.Swashbuckle/Microsoft/AspNetCore/Builder/AbpSwaggerUIBuilderExtensions.cs
index 79153cd487..f7d85e3256 100644
--- a/framework/src/Volo.Abp.Swashbuckle/Microsoft/AspNetCore/Builder/AbpSwaggerUIBuilderExtensions.cs
+++ b/framework/src/Volo.Abp.Swashbuckle/Microsoft/AspNetCore/Builder/AbpSwaggerUIBuilderExtensions.cs
@@ -9,7 +9,7 @@ public static class AbpSwaggerUIBuilderExtensions
 {
     public static IApplicationBuilder UseAbpSwaggerUI(
         this IApplicationBuilder app,
-        Action<SwaggerUIOptions> setupAction = null)
+        Action<SwaggerUIOptions>? setupAction = null)
     {
         var resolver = app.ApplicationServices.GetService<ISwaggerHtmlResolver>();
 
@@ -17,7 +17,7 @@ public static class AbpSwaggerUIBuilderExtensions
         {
             options.InjectJavascript("ui/abp.js");
             options.InjectJavascript("ui/abp.swagger.js");
-            options.IndexStream = () => resolver.Resolver();
+            options.IndexStream = () => resolver?.Resolver();
 
             setupAction?.Invoke(options);
         });
diff --git a/framework/src/Volo.Abp.Swashbuckle/Microsoft/Extensions/DependencyInjection/AbpSwaggerGenServiceCollectionExtensions.cs b/framework/src/Volo.Abp.Swashbuckle/Microsoft/Extensions/DependencyInjection/AbpSwaggerGenServiceCollectionExtensions.cs
index 0f5698ab08..13f1f2a296 100644
--- a/framework/src/Volo.Abp.Swashbuckle/Microsoft/Extensions/DependencyInjection/AbpSwaggerGenServiceCollectionExtensions.cs
+++ b/framework/src/Volo.Abp.Swashbuckle/Microsoft/Extensions/DependencyInjection/AbpSwaggerGenServiceCollectionExtensions.cs
@@ -12,7 +12,7 @@ public static class AbpSwaggerGenServiceCollectionExtensions
 {
     public static IServiceCollection AddAbpSwaggerGen(
         this IServiceCollection services,
-        Action<SwaggerGenOptions> setupAction = null)
+        Action<SwaggerGenOptions>? setupAction = null)
     {
         return services.AddSwaggerGen(
             options =>
@@ -34,7 +34,7 @@ public static class AbpSwaggerGenServiceCollectionExtensions
         this IServiceCollection services,
         [NotNull] string authority,
         [NotNull] Dictionary<string, string> scopes,
-        Action<SwaggerGenOptions> setupAction = null,
+        Action<SwaggerGenOptions>? setupAction = null,
         string authorizationEndpoint = "/connect/authorize",
         string tokenEndpoint = "/connect/token")
     {
@@ -82,10 +82,10 @@ public static class AbpSwaggerGenServiceCollectionExtensions
     public static IServiceCollection AddAbpSwaggerGenWithOidc(
         this IServiceCollection services,
         [NotNull] string authority,
-        string[] scopes = null,
-        string[] flows = null,
-        string discoveryEndpoint = null,
-        Action<SwaggerGenOptions> setupAction = null)
+        string[]? scopes = null,
+        string[]? flows = null,
+        string? discoveryEndpoint = null,
+        Action<SwaggerGenOptions>? setupAction = null)
     {
         var discoveryUrl = discoveryEndpoint != null ?
             new Uri(discoveryEndpoint) :
diff --git a/framework/src/Volo.Abp.Swashbuckle/Volo.Abp.Swashbuckle.csproj b/framework/src/Volo.Abp.Swashbuckle/Volo.Abp.Swashbuckle.csproj
index bbfce19981..83c25f3e23 100644
--- a/framework/src/Volo.Abp.Swashbuckle/Volo.Abp.Swashbuckle.csproj
+++ b/framework/src/Volo.Abp.Swashbuckle/Volo.Abp.Swashbuckle.csproj
@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFramework>net7.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <AssemblyName>Volo.Abp.Swashbuckle</AssemblyName>
         <PackageId>Volo.Abp.Swashbuckle</PackageId>
         <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/AbpSwashbuckleDocumentFilter.cs b/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/AbpSwashbuckleDocumentFilter.cs
index dd1b9705b8..d35443f98b 100644
--- a/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/AbpSwashbuckleDocumentFilter.cs
+++ b/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/AbpSwashbuckleDocumentFilter.cs
@@ -30,7 +30,7 @@ public class AbpSwashbuckleDocumentFilter : IDocumentFilter
             .RemoveAll(path => !actionUrls.Contains(path.Key));
     }
 
-    protected virtual string RemoveRouteParameterConstraints(ActionDescriptor actionDescriptor)
+    protected virtual string? RemoveRouteParameterConstraints(ActionDescriptor actionDescriptor)
     {
         var route = actionDescriptor.AttributeRouteInfo?.Template?.EnsureStartsWith('/').Replace("?", "");
         if (string.IsNullOrWhiteSpace(route))
diff --git a/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/SwaggerHtmlResolver.cs b/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/SwaggerHtmlResolver.cs
index 1826fd9336..628a361826 100644
--- a/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/SwaggerHtmlResolver.cs
+++ b/framework/src/Volo.Abp.Swashbuckle/Volo/Abp/Swashbuckle/SwaggerHtmlResolver.cs
@@ -13,7 +13,7 @@ public class SwaggerHtmlResolver : ISwaggerHtmlResolver, ITransientDependency
         var stream = typeof(SwaggerUIOptions).GetTypeInfo().Assembly
             .GetManifestResourceStream("Swashbuckle.AspNetCore.SwaggerUI.index.html");
 
-        var html = new StreamReader(stream)
+        var html = new StreamReader(stream!)
             .ReadToEnd()
             .Replace("SwaggerUIBundle(configObject)", "abp.SwaggerUIBundle(configObject)");