Error launching MAUI app on a device in Release Mode

[joehanna]

My large MAUI app builds successfully and runs on the iOS simulator and device in Debug mode, but it will not run in the simulator or device in Release mode.

I get this error (app name obfuscated):

/usr/local/share/dotnet/packs/Microsoft.iOS.Sdk.net9.0_26.0/26.0.9752/tools/bin/mlaunch --devname "Joe iPadPro 6th Gen" --killdev au.com.myapp.ib --launchdev /Users/joe/Projects/myapp/bin/Release/net9.0-ios/ios-arm64/myapp.app --wait-for-unlock --argument=-connection-mode --argument=usb -sdk 17.1 --sdkroot /Applications/Xcode.app/Contents/Developer
error MT0000: Unexpected error - Please file a bug report at https://github.com/xamarin/xamarin-macios/issues/new
System.InvalidOperationException: Nullable object must have a value.
   at System.Nullable`1.get_Value()
   at Xamarin.Launcher.DevController.LaunchDeviceUsingDeviceCtl(DeviceLaunchConfig, String) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/controller-device.cs:line 976
   at Xamarin.Launcher.Driver.LaunchOrDebugUsingDeviceCtl(Action, IRealDevice) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/Main.cs:line 577
   at Xamarin.Launcher.Driver.LaunchOrDebugAsync(Action) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/Main.cs:line 535
   at Xamarin.Launcher.Driver.MainAsync() in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/Main.cs:line 485
   at Xamarin.Utils.NSRunLoopExtensions.RunUntilTaskCompletion[T](NSRunLoop, Task`1) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Utils/Extensions.cs:line 29
   at Xamarin.Launcher.Driver.Main2(String[]) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/Main.cs:line 434
   at Xamarin.Launcher.Driver.Main(String[]) in /Users/builder/azdo/_work/4/s/src/Xamarin.Hosting/Xamarin.Launcher/Main.cs:line 125

I have checked around and seen posts by Rolf where I have added the Interpreter, I have also tried disabling AOT - all to no avail.

#23923
dotnet/maui#14271
MudBlazor/MudBlazor#6310
MudBlazor/MudBlazor#6558

It gets so frustrating building for MAUI - I spend more than half my time fighting the tooling.

I have tried VS on Windows, VS Insiders on Windows and Rider on Mac.

Everything is using the latest SDKs and O/S patches.

Please help! I am desperately trying to get an update out this weekend for critical changes.

Many thanks

[rolfbjarne]

This error happens when something else goes wrong when launching on device, but unfortunately it’s not very helpful. My guess is that something is wrong with provisioning, but that’s just a guess.

I would tap on the app to launch it, and at the same time look in the device log to see if anything useful is printed there when the app fails to launch (https://support.apple.com/en-in/guide/console/cnsl1012/mac)

[joehanna]

Thanks Rolf. I viewed all of the "Fault" and "Error" entries from the console (listed below), none of which stand out as the cause. I hope you can make sense of these and point me in the right direction.

I have tried different .NET 9 SDK versions from 9.0.103 to 9.0.306.

Console Faults

• UIScene lifecycle will soon be required. Failure to adopt will result in an assert in the future.
• Update the Info.plist: UIRequiresFullScreen will soon be ignored.

Console Errors

• SpringBoard - Snapshot generation request for bundleID: au.com.myapp.ib rejected due to the app being denylisted.
  kernel Sandbox: myapp(3104) deny(1) sysctl-read kern.bootargs
• SpringBoard - [0xb69582f40:(FBSceneManager):sceneID:au.com.myapp.ib-default] Scene creation failed: <NSError: 0xb64a06d30; domain: FBWorkspaceScene; code: 2 ("scene-creation-failed"); "Scene create failed. (null)">
• SpringBoard - "[(FBSceneManager):sceneID:au.com.myapp.ib-default] Update failed: <NSError: 0xb64375cb0; domain: FBSceneErrorDomain; code: 1 (""operation-failed""); ""Scene update failed.""> {
  NSUnderlyingError = <NSError: 0xb64a05c50; domain: BSServiceConnectionErrorDomain; code: 3 (""OperationFailed""); ""XPC error received on message reply handler"">;
  }"
• SpringBoard - Ignoring update for invalidated scene: (FBSceneManager):sceneID:au.com.myapp.ib-default
• symptomsd - Process state is unknown AppStateTracker, pid 3104, uuid 3FFD818A-F5BF-353C-8C54-94D6575D370C display identifier au.com.myapp.ib foreground 1
• symptomsd - COSMCtrl _foregroundAppActivity incoming bundle au.com.myapp.ib has nil supplied UUID, finds existing 3FFD818A-F5BF-353C-8C54-94D6575D370C
• SpringBoard - Snapshot generation request for bundleID: au.com.myapp.ib rejected due to the app being denylisted.
• kernel - Sandbox: myapp(3106) deny(1) sysctl-read kern.bootargs

[joehanna]

Not sure if it is related, but the app works perfectly in Debug mode but when I build the AppStore version and post it to TestFlight, the runtime behaviour is different. For instance, I have a Page that loads fine in Debug using PushAsync but fails in the AppStore version with this error:

Microsoft.Maui.Controls.ShadowTypeConverter..ctor()' is inaccessible from method

There is no documentation or discussions anywhere about this. I do not consume this class so I presume it is internal to MAUI.

I am having a really tough time trying to publish my app due to tooling/platform issues I have no control over or access to, and I would greatly appreciate any assistance you can provide.

Thank you

[rolfbjarne]

Not sure if it is related, but the app works perfectly in Debug mode but when I build the AppStore version and post it to TestFlight, the runtime behaviour is different. For instance, I have a Page that loads fine in Debug using PushAsync but fails in the AppStore version with this error:

Microsoft.Maui.Controls.ShadowTypeConverter..ctor()' is inaccessible from method

This is a different problem, so please file a new issue, otherwise it will get very confusing here.

[rolfbjarne]

Regarding the original issue here, run this command (this is the command from your original description, with "-vvvv" added at the end)

/usr/local/share/dotnet/packs/Microsoft.iOS.Sdk.net9.0_26.0/26.0.9752/tools/bin/mlaunch --devname "Joe iPadPro 6th Gen" --killdev au.com.myapp.ib --launchdev /Users/joe/Projects/myapp/bin/Release/net9.0-ios/ios-arm64/myapp.app --wait-for-unlock --argument=-connection-mode --argument=usb -sdk 17.1 --sdkroot /Applications/Xcode.app/Contents/Developer -vvvv

This will show a bit more info about what's going on, and among other things, it will show that it's executing a command like "xcrun devicectl ...".

Copy that command from the console output, and run it directly yourself, and that command will hopefully explain better why launching failed. Can you try this?

[joehanna]

Thanks so much Rolf for your quick response. I deleted the app off the device to start clean and ran the command as you asked. I did so with the device connected over Wifi and via USB. The logs for each are attached. Note - "myapp" is used to redact the actual app name.

The app doesn't install at all.

I just want to clarify all of the tooling versions in play. I am running Mac OS 26. I couldn't find anything clear on which versions are currently supported/recommended for .NET/Xcode/iOS. Should I be able to build .NET 9 apps on SDK 9.0.306 with Xcode 26? I use Rider on Mac but can also use VS on Windows if needed, which has VS2022 and VS2025 Preview.

myapp-build--dotnet-macios-gh24099.zip

[joehanna]

UPDATE: I reinstalled .NET 9 using the Installer and now the app will install and I don't get the original error message above, but it still will not launch in Release mode. I have attached the Xcode device console errors generated when launching.

myapp-console-errors--dotnet-macios-gh24099.xlsx.zip

[rolfbjarne]

What happens if you run this from the terminal (once the app is installed)?

$ xcrun devicectl -v device process launch --terminate-existing --device "Joe iPadPro 6th Gen" au.com.myapp.ib

This will avoid our tooling, and directly use Apple's command line tools to launch the app.

If the app isn't installed, do this first (after fixing the path to the app bundle):

$ xcrun devicectl -v device install app --device "Joe iPadPro 6th Gen" /Users/joe/Projects/myapp/bin/Release/net9.0-ios/ios-arm64/myapp.app