fix: Update fallback culture handling in AbpCultureMenuItemUrlProvider to use CurrentCulture instead of CurrentUICulture

docs/en/Community-Articles/2026-03-29-Url-Based-Localization/POST.md

@@ -93,7 +93,7 @@ Blazor WebAssembly (WebApp) is similar. The server renders the first page via SS
 |---|---|
 | **Culture detection** | `RouteDataRequestCultureProvider` reads `{culture}` from the URL on the initial HTTP request (SSR). |
 | **Cookie persistence** | The middleware saves the detected culture to the `.AspNetCore.Culture` cookie, which persists across the WebSocket connection. |
-| **Menu URLs** | `AbpCultureMenuItemUrlProvider` prepends the culture prefix. In Blazor interactive circuits (where `HttpContext` is unavailable), it falls back to `CultureInfo.CurrentUICulture`. |
+| **Menu URLs** | `AbpCultureMenuItemUrlProvider` prepends the culture prefix. In Blazor interactive circuits (where `HttpContext` is null — no active HTTP request), it falls back to `CultureInfo.CurrentCulture`. |
 | **Language switching** | The built-in `LanguageSwitch` component navigates to `/Abp/Languages/Switch` with `forceLoad: true`, triggering a full HTTP reload. The culture segment in the return URL is automatically replaced. |
 
 ### Important: Blazor component route limitation

docs/en/framework/fundamentals/url-based-localization.md

@@ -111,7 +111,7 @@ Blazor Server uses SignalR (WebSocket) for the interactive circuit. The HTTP mid
 |---|---|
 | **Culture detection** | `RouteDataRequestCultureProvider` reads `{culture}` from the URL on the initial HTTP request (SSR). |
 | **Cookie persistence** | The middleware automatically saves the detected culture to `.AspNetCore.Culture` cookie, which persists across the WebSocket connection. |
-| **Menu URLs** | `AbpCultureMenuItemUrlProvider` prepends the culture prefix. In the interactive circuit (where `HttpContext` has no route values), it falls back to `CultureInfo.CurrentUICulture`. |
+| **Menu URLs** | `AbpCultureMenuItemUrlProvider` prepends the culture prefix. In the interactive circuit (where `HttpContext` is null — no active HTTP request), it falls back to `CultureInfo.CurrentCulture`. |
 | **Language switching** | The built-in `LanguageSwitch` component navigates to `/Abp/Languages/Switch` with `forceLoad: true`, triggering a full HTTP reload. The culture segment in the return URL is automatically replaced. |
 
 ### What requires manual changes

framework/src/Volo.Abp.AspNetCore.Mvc/Volo/Abp/AspNetCore/Mvc/Localization/AbpCultureMenuItemUrlProvider.cs

@@ -62,9 +62,10 @@ public class AbpCultureMenuItemUrlProvider : IMenuItemUrlProvider
         }
 
         // Blazor interactive circuits: HttpContext is null because there is
-        // no active HTTP request. Fall back to CultureInfo.CurrentUICulture
-        // which was set by the middleware during SSR and persisted in the circuit.
-        var currentCulture = CultureInfo.CurrentUICulture.Name;
+        // no active HTTP request. Fall back to CultureInfo.CurrentCulture
+        // (set by the middleware during SSR and persisted in the circuit).
+        // CurrentCulture corresponds to the {culture} route segment, not ui-culture.
+        var currentCulture = CultureInfo.CurrentCulture.Name;
         var isKnownCulture = AbpLocalizationOptions.Value.Languages
             .Any(l => string.Equals(l.CultureName, currentCulture, StringComparison.OrdinalIgnoreCase));
 

framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/Localization/AbpCultureMenuItemUrlProvider_Tests.cs

@@ -51,24 +51,26 @@ public class AbpCultureMenuItemUrlProvider_Tests
     }
 
     [Fact]
-    public async Task Should_Use_CurrentUICulture_Fallback_When_No_HttpContext()
+    public async Task Should_Use_CurrentCulture_Fallback_When_No_HttpContext()
     {
-        // Simulates Blazor interactive circuit: no HttpContext, but CurrentUICulture is set
+        // Simulates Blazor interactive circuit: no HttpContext, but CurrentCulture is set.
+        // CurrentCulture (not CurrentUICulture) is used because {culture} route segments
+        // represent the culture, not the UI culture.
         var provider = CreateProviderWithoutHttpContext(
             useRouteBasedCulture: true,
             knownLanguages: new[] { "en", "zh-Hans", "tr" });
 
         var menu = CreateMenuWithItems("/home", "/about");
 
-        var previousCulture = CultureInfo.CurrentUICulture;
+        var previousCulture = CultureInfo.CurrentCulture;
         try
         {
-            CultureInfo.CurrentUICulture = new CultureInfo("zh-Hans");
+            CultureInfo.CurrentCulture = new CultureInfo("zh-Hans");
             await provider.HandleAsync(new MenuItemUrlProviderContext(menu));
         }
         finally
         {
-            CultureInfo.CurrentUICulture = previousCulture;
+            CultureInfo.CurrentCulture = previousCulture;
         }
 
         menu.Items[0].Url.ShouldBe("/zh-Hans/home");
@@ -85,15 +87,15 @@ public class AbpCultureMenuItemUrlProvider_Tests
 
         var menu = CreateMenuWithItems("/home", "/about");
 
-        var previousCulture = CultureInfo.CurrentUICulture;
+        var previousCulture = CultureInfo.CurrentCulture;
         try
         {
-            CultureInfo.CurrentUICulture = new CultureInfo("fr");
+            CultureInfo.CurrentCulture = new CultureInfo("fr");
             await provider.HandleAsync(new MenuItemUrlProviderContext(menu));
         }
         finally
         {
-            CultureInfo.CurrentUICulture = previousCulture;
+            CultureInfo.CurrentCulture = previousCulture;
         }
 
         menu.Items[0].Url.ShouldBe("/home");