System.IO.FileNotFoundException: The configuration file 'appsettings.json' was not found and is not optional.

Created March 03, 2025 18:47

I am using JetBrains Rider 2024.3.5 Build #RD-243.24978.27, built on February 6, 2025 on a Mac Studio 2023 M2 Ultra with 64GB RAM Sequoia 15.1, and Xcode Version 16.2 (16C5032a).

Full exception info further below:

Following are the steps you can use to reproduce this issue:

I have created a new C# Maui .Net 9 solution with sample data from your stock template.
I added added the Microsoft.Extensions.Configuration.Abstractions, Microsoft.Extensions.Configuration and Microsoft.Extensions.Configuration.Json.
I then right-click on solution → Add → Configuration Files → appsettings.json File and selected the same name with the default sample data. The build action is set to None and Copy always.
In MauiProgram.CreateMauiApp() I added the following lines:
var built = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
var child = built.GetChildren();
Set a breakpoint just below the above code.
Ran the project for MacCatalyst and received the following exception:

System.IO.FileNotFoundException: The configuration file 'appsettings.json' was not found and is not optional. The expected physical path was '/Volumes/Projects/Checklists/Checklists/bin/Debug/net9.0-maccatalyst/Checklists.app/Contents/MonoBundle/appsettings.json'.
at Microsoft.Extensions.Configuration.FileConfigurationProvider.HandleException(ExceptionDispatchInfo info)
at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load(Boolean reload)
at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load()
at Microsoft.Extensions.Configuration.ConfigurationRoot..ctor(IList`1 providers)
at Microsoft.Extensions.Configuration.ConfigurationBuilder.Build()
at Checklists.MauiProgram.CreateMauiApp() in /Volumes/Projects/Checklists/Checklists/MauiProgram.cs:line 110
at Checklists.AppDelegate.CreateMauiApp() in /Volumes/Projects/Checklists/Checklists/Platforms/MacCatalyst/AppDelegate.cs:line 29
at Microsoft.Maui.MauiUIApplicationDelegate.WillFinishLaunching(UIApplication application, NSDictionary launchOptions)
at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 61
at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:line 96
at Checklists.Program.Main(String[] args) in /Volumes/Projects/Checklists/Checklists/Platforms/MacCatalyst/Program.cs:line 17

2 comments

Tom Luo

Created March 05, 2025 16:38

Hello Kmwenyon,

Thank you for contacting JetBrains Support. I'm glad to work with you on this ticket.

This isn’t a Rider-specific issue. The issue is Appsetting.json is not natively supported in MAUI yet. See [Enhancement] Add appsettings support · Issue #4408 · dotnet/maui for more information.

You can find various ways online to work this around. The way that works for me is below:

Set "Build Action" of appsetting.json to "Emebded Resources"
Update the code as below:

        var asm = Assembly.GetExecutingAssembly();
        var path = $"{asm.GetName().Name}.appsettings.json";
        using Stream stream = asm.GetManifestResourceStream(path);
        var built = new ConfigurationBuilder().AddJsonStream(stream).Build();
        var child = built.GetChildren();

For additional context, see this StackOverflow issue that demonstrates this pattern in MAUI environments.

Let me know if you have any other questions.

Regards,

Tom

Kmwenyon

Created March 05, 2025 16:40

Thank you

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