diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo.Abp.UI.Navigation.csproj b/framework/src/Volo.Abp.UI.Navigation/Volo.Abp.UI.Navigation.csproj
index 65b07f1579..e23d96950e 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo.Abp.UI.Navigation.csproj
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo.Abp.UI.Navigation.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.UI.Navigation</AssemblyName>
     <PackageId>Volo.Abp.UI.Navigation</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenu.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenu.cs
index 9f48aebf97..d38279b1cd 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenu.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenu.cs
@@ -26,7 +26,7 @@ public class ApplicationMenu : IHasMenuItems, IHasMenuGroups
             _displayName = value;
         }
     }
-    private string _displayName;
+    private string _displayName = default!;
 
     /// <inheritdoc cref="IHasMenuItems.Items"/>
     [NotNull]
@@ -44,7 +44,7 @@ public class ApplicationMenu : IHasMenuItems, IHasMenuGroups
 
     public ApplicationMenu(
         [NotNull] string name,
-        string displayName = null)
+        string? displayName = null)
     {
         Check.NotNullOrWhiteSpace(name, nameof(name));
 
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuExtensions.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuExtensions.cs
index 624abde425..59814ff3be 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuExtensions.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuExtensions.cs
@@ -29,8 +29,7 @@ public static class ApplicationMenuExtensions
         return menuItem;
     }
 
-    [CanBeNull]
-    public static ApplicationMenuItem GetMenuItemOrNull(
+    public static ApplicationMenuItem? GetMenuItemOrNull(
         [NotNull] this IHasMenuItems menuWithItems,
         string menuItemName)
     {
@@ -79,8 +78,7 @@ public static class ApplicationMenuExtensions
         return menuGroup;
     }
 
-    [CanBeNull]
-    public static ApplicationMenuGroup GetMenuGroupOrNull(
+    public static ApplicationMenuGroup? GetMenuGroupOrNull(
         [NotNull] this IHasMenuGroups menuWithGroups,
         string menuGroupName)
     {
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuGroup.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuGroup.cs
index 8d29e99552..ab76c1c337 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuGroup.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuGroup.cs
@@ -4,8 +4,8 @@ namespace Volo.Abp.UI.Navigation;
 
 public class ApplicationMenuGroup
 {
-    private string _displayName;
-    private string _elementId;
+    private string _displayName = default!;
+    private string? _elementId;
 
     /// <summary>
     /// Default <see cref="Order"/> value of a group item.
@@ -33,7 +33,7 @@ public class ApplicationMenuGroup
     /// <summary>
     /// Can be used to render the element with a specific Id for DOM selections.
     /// </summary>
-    public string ElementId {
+    public string? ElementId {
         get { return _elementId; }
         set {
             _elementId = NormalizeElementId(value);
@@ -49,7 +49,7 @@ public class ApplicationMenuGroup
     public ApplicationMenuGroup(
         [NotNull] string name,
         [NotNull] string displayName,
-        string elementId = null,
+        string? elementId = null,
         int order = DefaultOrder)
     {
         Check.NotNullOrWhiteSpace(name, nameof(name));
@@ -57,7 +57,7 @@ public class ApplicationMenuGroup
 
         Name = name;
         DisplayName = displayName;
-        ElementId = elementId;
+        ElementId = elementId ?? GetDefaultElementId();
         Order = order;
     }
 
@@ -66,7 +66,7 @@ public class ApplicationMenuGroup
         return "MenuGroup_" + Name;
     }
 
-    private string NormalizeElementId(string elementId)
+    private string? NormalizeElementId(string? elementId)
     {
         return elementId?.Replace(".", "_");
     }
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuItem.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuItem.cs
index 54bd591469..0c42a15c5e 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuItem.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/ApplicationMenuItem.cs
@@ -7,8 +7,8 @@ namespace Volo.Abp.UI.Navigation;
 
 public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<ApplicationMenuItem>
 {
-    private string _displayName;
-    private string _elementId;
+    private string _displayName = default!;
+    private string? _elementId;
 
     /// <summary>
     /// Default <see cref="Order"/> value of a menu item.
@@ -42,14 +42,12 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
     /// <summary>
     /// The URL to navigate when this menu item is selected.
     /// </summary>
-    [CanBeNull]
-    public string Url { get; set; }
+    public string? Url { get; set; }
 
     /// <summary>
     /// Icon of the menu item if exists.
     /// </summary>
-    [CanBeNull]
-    public string Icon { get; set; }
+    public string? Icon { get; set; }
 
     /// <summary>
     /// Returns true if this menu item has no child <see cref="Items"/>.
@@ -59,8 +57,7 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
     /// <summary>
     /// Target of the menu item. Can be null, "_blank", "_self", "_parent", "_top" or a frame name for web applications.
     /// </summary>
-    [CanBeNull]
-    public string Target { get; set; }
+    public string? Target { get; set; }
 
     /// <summary>
     /// Can be used to disable this menu item.
@@ -71,9 +68,8 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
     [NotNull]
     public ApplicationMenuItemList Items { get; }
 
-    [CanBeNull]
     [Obsolete("Use RequirePermissions extension method.")]
-    public string RequiredPermissionName { get; set; }
+    public string? RequiredPermissionName { get; set; }
 
     public List<ISimpleStateChecker<ApplicationMenuItem>> StateCheckers { get; }
 
@@ -86,7 +82,7 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
     /// <summary>
     /// Can be used to render the element with a specific Id for DOM selections.
     /// </summary>
-    public string ElementId {
+    public string? ElementId {
         get { return _elementId; }
         set {
             _elementId = NormalizeElementId(value);
@@ -96,24 +92,24 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
     /// <summary>
     /// Can be used to render the element with extra CSS classes.
     /// </summary>
-    public string CssClass { get; set; }
+    public string? CssClass { get; set; }
 
     /// <summary>
     /// Can be used to group menu items.
     /// </summary>
-    public string GroupName { get; set; }
+    public string? GroupName { get; set; }
 
     public ApplicationMenuItem(
         [NotNull] string name,
         [NotNull] string displayName,
-        string url = null,
-        string icon = null,
+        string? url = null,
+        string? icon = null,
         int order = DefaultOrder,
-        string target = null,
-        string elementId = null,
-        string cssClass = null,
-        string groupName = null,
-        string requiredPermissionName = null)
+        string? target = null,
+        string? elementId = null,
+        string? cssClass = null,
+        string? groupName = null,
+        string? requiredPermissionName = null)
     {
         Check.NotNullOrWhiteSpace(name, nameof(name));
         Check.NotNullOrWhiteSpace(displayName, nameof(displayName));
@@ -158,7 +154,7 @@ public class ApplicationMenuItem : IHasMenuItems, IHasSimpleStateCheckers<Applic
         return "MenuItem_" + Name;
     }
     
-    private string NormalizeElementId(string elementId)
+    private string? NormalizeElementId(string? elementId)
     {
         return elementId?.Replace(".", "_");
     }
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/HasMenuItemsExtensions.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/HasMenuItemsExtensions.cs
index 4d0f0d38a1..d712c8d931 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/HasMenuItemsExtensions.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/HasMenuItemsExtensions.cs
@@ -5,8 +5,7 @@ namespace Volo.Abp.UI.Navigation;
 
 public static class HasMenuItemsExtensions
 {
-    [CanBeNull]
-    public static ApplicationMenuItem FindMenuItem(this IHasMenuItems container, string menuItemName)
+    public static ApplicationMenuItem? FindMenuItem(this IHasMenuItems container, string menuItemName)
     {
         foreach (var menuItem in container.Items)
         {
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuConfigurationContext.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuConfigurationContext.cs
index d3ce40c99a..c095f71861 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuConfigurationContext.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuConfigurationContext.cs
@@ -32,8 +32,7 @@ public class MenuConfigurationContext : IMenuConfigurationContext
         return AuthorizationService.IsGrantedAsync(policyName);
     }
 
-    [CanBeNull]
-    public IStringLocalizer GetDefaultLocalizer()
+    public IStringLocalizer? GetDefaultLocalizer()
     {
         return StringLocalizerFactory.CreateDefaultOrNull();
     }
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuManager.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuManager.cs
index 349aa8e5a5..907779c397 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuManager.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/MenuManager.cs
@@ -165,7 +165,7 @@ public class MenuManager : IMenuManager, ITransientDependency
     {
         foreach (var menuGroup in applicationMenu.Items.Where(x => !x.GroupName.IsNullOrWhiteSpace()).GroupBy(x => x.GroupName))
         {
-            var group = applicationMenu.GetMenuGroupOrNull(menuGroup.First().GroupName);
+            var group = applicationMenu.GetMenuGroupOrNull(menuGroup.First().GroupName!);
             if (group != null)
             {
                 continue;
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/AppUrlProvider.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/AppUrlProvider.cs
index ff1db3a772..17a4e684e9 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/AppUrlProvider.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/AppUrlProvider.cs
@@ -33,7 +33,7 @@ public class AppUrlProvider : IAppUrlProvider, ITransientDependency
         Logger = NullLogger<AppUrlProvider>.Instance;
     }
 
-    public virtual async Task<string> GetUrlAsync(string appName, string urlName = null)
+    public virtual async Task<string> GetUrlAsync(string appName, string? urlName = null)
     {
         return await ReplacePlaceHoldersAsync(
             await GetConfiguredUrl(
@@ -53,12 +53,12 @@ public class AppUrlProvider : IAppUrlProvider, ITransientDependency
         return allow;
     }
 
-    protected virtual async Task<string> GetConfiguredUrl(string appName, string urlName)
+    protected virtual async Task<string> GetConfiguredUrl(string appName, string? urlName)
     {
         var url = await GetUrlOrNullAsync(appName, urlName);
         if (!url.IsNullOrEmpty())
         {
-            return url;
+            return url!;
         }
 
         if (!urlName.IsNullOrEmpty())
@@ -115,10 +115,10 @@ public class AppUrlProvider : IAppUrlProvider, ITransientDependency
             return tenantConfiguration.Name;
         }
 
-        return CurrentTenant.Name;
+        return CurrentTenant.Name!;
     }
 
-    public Task<string> GetUrlOrNullAsync([NotNull] string appName, [CanBeNull] string urlName = null)
+    public Task<string?> GetUrlOrNullAsync([NotNull] string appName, string? urlName = null)
     {
         var app = Options.Applications[appName];
 
@@ -127,13 +127,13 @@ public class AppUrlProvider : IAppUrlProvider, ITransientDependency
             return Task.FromResult(app.RootUrl);
         }
 
-        var url = app.Urls.GetOrDefault(urlName);
+        var url = app.Urls.GetOrDefault(urlName!);
 
         if (app.RootUrl == null)
         {
             return Task.FromResult(url);
         }
 
-        return Task.FromResult(app.RootUrl.EnsureEndsWith('/') + url);
+        return Task.FromResult<string?>(app.RootUrl.EnsureEndsWith('/') + url);
     }
 }
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/ApplicationUrlInfo.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/ApplicationUrlInfo.cs
index 3e57fadcae..0e00c8039c 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/ApplicationUrlInfo.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/ApplicationUrlInfo.cs
@@ -4,7 +4,7 @@ namespace Volo.Abp.UI.Navigation.Urls;
 
 public class ApplicationUrlInfo
 {
-    public string RootUrl { get; set; }
+    public string? RootUrl { get; set; }
 
     public IDictionary<string, string> Urls { get; }
 
diff --git a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/IAppUrlProvider.cs b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/IAppUrlProvider.cs
index 51f6a56afa..9241c5f428 100644
--- a/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/IAppUrlProvider.cs
+++ b/framework/src/Volo.Abp.UI.Navigation/Volo/Abp/Ui/Navigation/Urls/IAppUrlProvider.cs
@@ -5,9 +5,9 @@ namespace Volo.Abp.UI.Navigation.Urls;
 
 public interface IAppUrlProvider
 {
-    Task<string> GetUrlAsync([NotNull] string appName, [CanBeNull] string urlName = null);
+    Task<string> GetUrlAsync([NotNull] string appName, string? urlName = null);
 
-    Task<string> GetUrlOrNullAsync([NotNull] string appName, [CanBeNull] string urlName = null);
+    Task<string?> GetUrlOrNullAsync([NotNull] string appName, string? urlName = null);
 
     bool IsRedirectAllowedUrl(string url);
 }