New WinUI 3 projects fail to build with CS1061 errors after a fresh OS and VS install.
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glen burke
0
Reputation points
The error always appears in the generated file MainWindow.g.cs. This indicates that the XAML compiler is not correctly connecting the UI file to the code-behind file.
Troubleshooting Steps Already Taken:
I have already performed extensive troubleshooting, including:
Rebuilding the solution multiple times.
Cleaning the solution and manually deleting the bin, obj, and .vs folders.
Running dotnet restore from the Developer PowerShell.
Running the "Repair" feature from the Visual Studio Installer.
Performing a full factory reset of Windows and a fresh install.
After the factory reset, performing a fresh install of Visual Studio 2022 Community and also Visual Studio 2022 Preview.
During the installation, I selected the following workloads:
.NET desktop development
Universal Windows Platform development
Desktop development with C++
WinUI application development
The error persists even after a complete OS and Visual Studio reinstall, on both the stable and preview versions of Visual Studio. This seems to be a fundamental issue with the build tools or the SDK installation on my machine.
Any help would be greatly appreciated. Thank you.
Developer technologies | Visual Studio | Setup
{count} votes
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Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 245 Reputation points Microsoft External Staff2025-08-04T11:47:25.7933333+00:00 Steps to Solve
- Ensure .NET 6 or .NET 7 SDK is installed:
Download from .NET SDK Downloads WinUI 3 (via Windows App SDK) requires correct SDK version.
- Install the Windows App SDK and go to Windows App SDK Installer
Install latest stable version (e.g., 1.4 or 1.5)
- Open Visual Studio Installer Modify Installation: Make sure these workloads are selected:
.NET Desktop Development
Universal Windows Platform development
Desktop development with C++
WinUI application development
- Enable XAML Intellisense/Build tools: In Visual Studio > Tools > Options > XAML > Miscellaneous, ensure
"Enable XAML Designer" is ✅ enabled.
"Always recompile XAML" is ✅ checked.
- Delete intermediate files: Close VS,Delete bin, obj, and .vs folders manually,Reopen solution.
- Rebuild with Admin Rights: Open Developer PowerShell for VS as Admin.
Run: dotnet clean, dotnet build
- Check MainWindow.xaml & MainWindow.xaml.cs linkage:
Ensure XAML root tag contains x:Class="YourProject.MainWindow"
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Surya Amrutha Vaishnavi Lanka (INFOSYS LIMITED) 245 Reputation points Microsoft External Staff
2025-08-12T05:29:56.5133333+00:00 Hope you're doing well , we're following up on the ticket. Please let us know issue persist are resolved.
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