Xamarin Forms XAML本地化报错：资源文件扩展名异常咨询

Hey, I’ve run into this exact problem before—super frustrating when the resource files get mislabeled as .resources instead of using the standard .resx/.resw that ResourceManager expects! Let’s walk through how to fix this step by step:

1. Verify Resource File Properties #

First, check the build action and custom tool settings for your resource files—this is usually the root cause:

• In Solution Explorer, right-click your .resx/.resw file and select Properties.
• For .resx files (shared across Xamarin.Forms projects):
  • Set Build Action to Embedded Resource
  • Set Custom Tool to ResXFileCodeGenerator (this generates the strongly-typed resource class that ResourceManager uses)
• For .resw files (UWP-specific):
  • Set Build Action to PRIResource (no custom tool needed here, UWP handles it automatically)

2. Explicitly Target Resource Files in Your TranslateExtension #

Make sure your TranslateExtension code is pointing to the correct resource file name (without any .resources suffix). Here’s an example of how to initialize the ResourceManager properly:

[ContentProperty(nameof(Text))]
public class TranslateExtension : IMarkupExtension
{
    public string Text { get; set; }

    public object ProvideValue(IServiceProvider serviceProvider)
    {
        if (Text == null) return string.Empty;
        
        // Use your project's namespace + resource file name (without .resx)
        var resourceManager = new ResourceManager("YourAppNamespace.Resources.AppResources", typeof(App).Assembly);
        return resourceManager.GetString(Text, CultureInfo.CurrentUICulture);
    }
}

The key here is using the full qualified name of your resource file (e.g., YourAppNamespace.Resources.AppResources for a file named AppResources.resx in a Resources folder) instead of relying on auto-detection that might pick up the .resources artifact.

3. Clean and Rebuild Your Solution #

Old build artifacts can stick around and cause this issue. Do a full clean:

• Go to Build > Clean Solution
• Manually delete the bin and obj folders from all your project directories
• Then run Build > Rebuild Solution
  This ensures any leftover .resources files are removed and the new build uses your proper .resx/.resw files.

4. Double-Check Resource File Naming & Location #

• Make sure your resource files are named correctly (e.g., AppResources.resx for default culture, AppResources.es.resx for Spanish)
• Keep them in a dedicated folder like Resources to avoid namespace confusion
• Never manually rename the file extension to .resources—let Visual Studio handle the build artifacts automatically

That should get your TranslateExtension working with standard .resx/.resw files again!

内容的提问来源于stack exchange，提问作者Bjorn Fontaine