Issue to the bug

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Issue to the bug

Jonathan 270

Hi,

Can you help to the bug below? Which event is causing the issue?

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Answer accepted by question author

Nancy Vo (WICLOUD CORPORATION) 6,510 Microsoft External Staff Moderator

Hello @Jonathan ,

Thanks for your question.

In your screenshot, the code is doing some PDF paperwork. However, when it is done with the PDF task, it never actually builds or returns the application. The method just ends.

The compiler is throwing the CS0161 error because the factory broke its contract—the operating system is waiting for an app, but the method didn't return one.

I recommend returning statement at the very end. You can refer to following code example:

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();

        builder.UseMauiApp<App>();

        // Drop your PDF testing script here for now
        // string inputFilePath = @"C:\path\to\your\input.pdf";
        // ... rest of the try/catch logic ...

        return builder.Build();
    }

    // Keep the PDF helper method outside the main builder
    // public static void InjectTextIntoPdf(...)
}

I hope this addresses your question. If this response was helpful, please consider following the guidance to provide feedback.

Jonathan 270 Reputation points

2026-06-23T09:45:03.3133333+00:00

Thanks a lot. Can you help?

Nancy Vo (WICLOUD CORPORATION) 6,510 Microsoft External Staff Moderator

Hi @Jonathan ,

Your project has the .NET MAUI Community Toolkit installed. Right now, the code sets up the main app (builder.UseMauiApp<App>()) but forgets to register the toolkit. You just need to add .UseMauiCommunityToolkit() directly to that setup code.

The C# programming language is strictly case-sensitive. The command required to finish creating the app is Build() with a capital B. Because it was typed with a lowercase b (build()), the system does not recognize the command and cannot proceed.

You can refer to the following code example:


using CommunityToolkit.Maui;

public static class MauiProgram

{

    public static MauiApp CreateMauiApp()

    {

        var builder = MauiApp.CreateBuilder();

        builder

            .UseMauiApp<App>()

            .UseMauiCommunityToolkit();

        string inputFilePath = @"C:\path\to\your\input.pdf";

        string outputFilePath = @"C:\path\to\your\output_injected.pdf";

        string textToInject = "CONFIDENTIAL: INTERNAL USE ONLY";

        try

        {

            InjectTextIntoPdf(inputFilePath, outputFilePath, textToInject);

            Console.WriteLine("Text injected successfully!");

        }

        catch (Exception ex)

        {

            Console.WriteLine($"An error occurred: {ex.Message}");

        }

        return builder.Build();

    }

}

Hope this helps. Please feel free to reach out if you have any questions.

Jonathan 270 Reputation points

2026-06-24T03:08:23.67+00:00

Can you help?
Nancy Vo (WICLOUD CORPORATION) 6,510 Reputation points Microsoft External Staff Moderator

2026-06-24T03:33:00.9866667+00:00

Hi @Jonathan ,
As mentioned in my previous comment, could you please try replacing build() with Build() and see if that resolves the issue? Please let me know the result. Thank you

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Jonathan 270 Reputation points

2026-06-23T09:45:03.3133333+00:00

Thanks a lot. Can you help?
Nancy Vo (WICLOUD CORPORATION) 6,510 Reputation points Microsoft External Staff Moderator

2026-06-23T09:55:21.54+00:00

Hi @Jonathan ,

Your project has the .NET MAUI Community Toolkit installed. Right now, the code sets up the main app (builder.UseMauiApp<App>()) but forgets to register the toolkit. You just need to add .UseMauiCommunityToolkit() directly to that setup code.

The C# programming language is strictly case-sensitive. The command required to finish creating the app is Build() with a capital B. Because it was typed with a lowercase b (build()), the system does not recognize the command and cannot proceed.

You can refer to the following code example:

using CommunityToolkit.Maui; public static class MauiProgram { public static MauiApp CreateMauiApp() { var builder = MauiApp.CreateBuilder(); builder .UseMauiApp<App>() .UseMauiCommunityToolkit(); string inputFilePath = @"C:\path\to\your\input.pdf"; string outputFilePath = @"C:\path\to\your\output_injected.pdf"; string textToInject = "CONFIDENTIAL: INTERNAL USE ONLY"; try { InjectTextIntoPdf(inputFilePath, outputFilePath, textToInject); Console.WriteLine("Text injected successfully!"); } catch (Exception ex) { Console.WriteLine($"An error occurred: {ex.Message}"); } return builder.Build(); } }

Hope this helps. Please feel free to reach out if you have any questions.
Jonathan 270 Reputation points

2026-06-24T03:08:23.67+00:00

Can you help?
Nancy Vo (WICLOUD CORPORATION) 6,510 Reputation points Microsoft External Staff Moderator

2026-06-24T03:33:00.9866667+00:00

Hi @Jonathan ,
As mentioned in my previous comment, could you please try replacing build() with Build() and see if that resolves the issue? Please let me know the result. Thank you

Answer 1

The error is raised by the CreateMauiApp() method itself.

CreateMauiApp() is declared with a return type (most likely MauiApp), but in the code shown there is no return statement. That’s why the compiler reports:

MauiProgram.CreateMauiApp(): not all code paths return a value

To fix it, ensure that every execution path in CreateMauiApp() ends with a return of the appropriate object, for example:

public static MauiApp CreateMauiApp()
{
    // your setup code

    return builder.Build();   // or whatever object CreateMauiApp is supposed to return
}

References:

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