Hot reload doesn't work with WinUI 3

[kostya9]

Describe the bug

C# hot reload doesn't work with the default WinUI 3 project

Steps to reproduce the bug

1. Create new WinUI3 project
2. Run in Debug mode and (Packaged) configuratoion
3. Try to edit the button content assignment to other text
4. Click hot reload

Actual: Error message box with text "Hot Reload can't ..."

Expected behavior

Hot reload is successful

Screenshots

NuGet package version

WinUI 3 - Windows App SDK 1.1 Preview 2: 1.1.0-preview2

Windows app type

• UWP
• Win32

Device form factor

Desktop

Windows version

Windows 11 (21H2): Build 22000

Additional context

Tried Visual Studio 2022 17.1, Visual Studio 2022 17.2 Preview 5.0
Tried .NET 6, .NET 7 preview
Tried Microsoft.WindowsAppSDK Versions 1.0.0, 1.0.3, 1.1.0-preview2

Cannot try with "Unpackaged" configuration since it throws "Unable to load DLL 'Microsoft.ui.xaml.dll' or one of its dependencies: The specified module could not be found. (0x8007007E)" on startup (#6377)

[castorix]

It works fine for me : WinUI 3, Windows App SDK 1.1.0-preview2, Windows 10 21H1.
Test Unpackaged app :

[kmgallahan]

XAML hot reload is mostly reliable outside of bindings.

C# hot reload sometimes works, but you must do step 2 here.

Make sure that Enable native code debugging is disabled in the debugger settings or the debug launch profile.

Other unsupported scenarios

[kostya9]

I think I figured it out...

@kmgallahan thanks for the pointer

VS Debug profile says that native debugging is disabled, but it didn't allow hot reloading for some reason.

However, as soon as I added "nativeDebugging": false to the launchSettings.json, the C# hot reloading feature started working.

{
  "profiles": {
    "WinUi3App (Package)": {
      "commandName": "MsixPackage",
+     "nativeDebugging": false
    },
    "WinUi3App (Unpackaged)": {
      "commandName": "Project"
    }
  }
}

---

It seems like there are some synchronisation issues between the VS Debug Properties and what is actually used to run the app.

[marb2000]

Actually, XAML Hot Reload doesn't work with succinct RowDefinition:

<Grid RowDefinitions="Auto, Auto, *, Auto">

[heartacker]

I have the same issue.
And I had try to using Unpackaged launch config ,but I face the error #6377 (comment)

[jpgarza93]

Removing this did it for me.

Actually, XAML Hot Reload doesn't work with succinct RowDefinition:

<Grid RowDefinitions="Auto, Auto, *, Auto">

wow

[lukasf]

It seems to be a problem in WinUI 3: #673

[AMArostegui]

In my case, XAML hot reload only works when running a x86 application, not for x64 or Any Cpu configurations

[manusoft]

Actually, XAML Hot Reload doesn't work with succinct RowDefinition:

<Grid RowDefinitions="Auto, Auto, *, Auto">

Remove RowDefinitions it works.. great!

[Reza-Noei]

Thanks @marb2000 it worked for me too !

But it's a bug actually, Any plan to resolve it ?
Because it saves my time and reduces a lots of spaces in the code.

[evelynwu-msft]

Original issue is solved (#7043 (comment)), known limitation in C# hot reload, unrelated to WinUI 3. Subsequent comments are duplicate reports of #5944.