[RC1] Blazor WASM respects UI culture setting (#36105)

Author: guardrex

aspnetcore/blazor/globalization-localization.md

@@ -363,8 +363,12 @@ CultureInfo.DefaultThreadCurrentCulture = new CultureInfo("en-US");
 CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("en-US");
 ```
 
+:::moniker range="< aspnetcore-10.0"
+
 > [!NOTE]
-> Currently, Blazor WebAssembly apps only load resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture>. For more information, see [Blazor WASM only relies on the current culture (current UI culture isn't respected) (`dotnet/aspnetcore` #56824)](https://github.com/dotnet/aspnetcore/issues/56824).
+> In .NET 9 or earlier, standalone Blazor WebAssembly apps load UI globalization resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture?displayProperty=nameWithType>. If you want to additionally load globalization data for your localization culture defined by <xref:System.Globalization.CultureInfo.DefaultThreadCurrentUICulture?displayProperty=nameWithType>, [upgrade the app to .NET 10 or later](xref:migration/index).
+
+:::moniker-end
 
 Use the `CultureExample1` component shown in the [Demonstration component](#demonstration-component) section to study how globalization works. Issue a request with United States English (`en-US`). Switch to Costa Rican Spanish (`es-CR`) in the browser's language settings. Request the webpage again. When the requested language is Costa Rican Spanish, the app's culture remains United States English (`en-US`).
 
@@ -507,8 +511,12 @@ CultureInfo.DefaultThreadCurrentUICulture = culture;
 await host.RunAsync();
 ```
 
+:::moniker range="< aspnetcore-10.0"
+
 > [!NOTE]
-> Currently, Blazor WebAssembly apps only load resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture>. For more information, see [Blazor WASM only relies on the current culture (current UI culture isn't respected) (`dotnet/aspnetcore` #56824)](https://github.com/dotnet/aspnetcore/issues/56824).
+> In .NET 9 or earlier, standalone Blazor WebAssembly apps load UI globalization resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture?displayProperty=nameWithType>. If you want to additionally load globalization data for your localization culture defined by <xref:System.Globalization.CultureInfo.DefaultThreadCurrentUICulture?displayProperty=nameWithType>, [upgrade the app to .NET 10 or later](xref:migration/index).
+
+:::moniker-end
 
 The following `CultureSelector` component shows how to perform the following actions:
 
@@ -1004,8 +1012,16 @@ CultureInfo.DefaultThreadCurrentUICulture = culture;
 await host.RunAsync();
 ```
 
+:::moniker-end
+
+:::moniker range=">= aspnetcore-8.0 < aspnetcore-10.0"
+
 > [!NOTE]
-> Currently, Blazor WebAssembly apps only load resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture>. For more information, see [Blazor WASM only relies on the current culture (current UI culture isn't respected) (`dotnet/aspnetcore` #56824)](https://github.com/dotnet/aspnetcore/issues/56824).
+> In .NET 9 or earlier, standalone Blazor WebAssembly apps load UI globalization resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture?displayProperty=nameWithType>. If you want to additionally load globalization data for your localization culture defined by <xref:System.Globalization.CultureInfo.DefaultThreadCurrentUICulture?displayProperty=nameWithType>, [upgrade the app to .NET 10 or later](xref:migration/index).
+
+:::moniker-end
+
+:::moniker range=">= aspnetcore-8.0"
 
 Add the following `CultureSelector` component to the `.Client` project.
 

aspnetcore/release-notes/aspnetcore-10.0.md

@@ -4,7 +4,7 @@ author: wadepickett
 description: Learn about the new features in ASP.NET Core in .NET 10.
 ms.author: wpickett
 ms.custom: mvc
-ms.date: 09/09/2025
+ms.date: 09/15/2025
 uid: aspnetcore-10
 ---
 # What's new in ASP.NET Core in .NET 10

aspnetcore/release-notes/aspnetcore-10/includes/blazor.md

@@ -759,3 +759,7 @@ public int CounterNotRestoredOnReconnect { get; set; }
 ```
 
 Call `PersistentComponentState.RegisterOnRestoring` to register a callback for imperatively controlling how state is restored, similar to how <xref:Microsoft.AspNetCore.Components.PersistentComponentState.RegisterOnPersisting%2A?displayProperty=nameWithType> provides full control of how state is persisted.
+
+### Blazor WebAssembly respects the current UI culture setting
+
+In .NET 9 or earlier, standalone Blazor WebAssembly apps load UI globalization resources based on <xref:System.Globalization.CultureInfo.DefaultThreadCurrentCulture?displayProperty=nameWithType>. If you want to additionally load globalization data for your localization culture defined by <xref:System.Globalization.CultureInfo.DefaultThreadCurrentUICulture?displayProperty=nameWithType>, [upgrade the app to .NET 10 or later](xref:migration/index).