Toolchain Requirements

Current Vite toolchain: Visual Studio 2026 with MSVC 14.50 and Windows SDK 10.0.26100. Uninstall or deselect every other MSVC toolset. A mismatched toolchain does not produce a clear error — it produces C4668: '__has_feature' is not defined and similar noise.

Compiling Unreal Engine Vite from source requires a specific, pinned set of build tools. Unreal Build Tool picks a toolchain by scanning what is installed, so having several MSVC versions side by side is the single most common cause of build failure. Install exactly what this page lists and remove the rest.

Supported toolchains

Vite is validated against the following combinations. The first row is the current recommendation.

The ViteSetup.bat assistant currently hard-pins Visual Studio 2022, MSVC 14.44 and Windows SDK 10.0.26100 subversion 7705 or higher, and refuses to continue otherwise. If you are on the VS 2026 / MSVC 14.50 toolchain, run the build steps manually rather than through the assistant, or update the REQUIRED_* variables at the top of the script. See ViteSetup Assistant.

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Required components

Install these through the Visual Studio Installer, under Individual components.

• Desktop development with C++ workload
• MSVC v14.50 – VS 2026 C++ x64/x86 build tools (or the version matching your chosen row above)
• Windows 11 SDK (10.0.26100)
• .NET Framework 4.6.2 targeting pack — required by UnrealBuildTool and AutomationTool
• .NET Framework 4.5 targeting pack — required by SwarmAgent, SwarmCoordinator, NetworkProfiler and UnrealControls

To skip the manual component selection, download and import the Vite VSConfig file through the Visual Studio 26 Installer's Import configuration option.

Removing conflicting toolsets

Open the Visual Studio Installer. Find your Visual Studio installation and click Modify. Switch to the Individual components tab. Uncheck every MSVC v14.x x64/x86 build tools entry except the one your chosen toolchain requires. Uncheck every Windows SDK except the one your chosen toolchain requires. Click Modify and let the installer finish before generating project files again.

Having more than one Windows SDK installed is not fatal, but it is a frequent source of link-time surprises. If you can get to exactly one, do.

The .NET Framework 4.5 targeting pack

The Visual Studio 2022 and 2026 installers no longer ship the 4.5 targeting pack, but the engine's C# tools still need it. A folder at C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5 that contains only XML files is a stub left behind by the .NET runtime, not a real targeting pack. Check for v4.5\RedistList\FrameworkList.xml to tell the difference.

ViteSetup.bat offers to install it automatically from the official Microsoft NuGet package. To do it by hand:

Download Microsoft.NETFramework.ReferenceAssemblies.net45 1.0.3. Open the .nupkg file as a ZIP archive. Copy build.NETFramework\v4.5 into C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5. This needs administrator rights. Confirm that v4.5\RedistList\FrameworkList.xml now exists.

Pinning the SDK through BuildConfiguration.xml

Unreal Build Tool reads a per-user configuration file that overrides its toolchain autodetection. This is the reliable way to force a specific Compiler and Windows SDK when several are present.

Edit (VS26):

%APPDATA%\Unreal Engine\UnrealBuildTool\BuildConfiguration.xml

<?xml version="1.0" encoding="utf-8"?>
<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
  <WindowsPlatform>
    <CompilerVersion>14.50</CompilerVersion> <!--Vite has been tested with MSVC 14.50 for about 9 months to this date -->
    <!--<CompilerVersion>14.44</CompilerVersion> VS22 Option: Latest Epic's 4.27 compliance -->
    <!--<CompilerVersion>14.29</CompilerVersion> Original 4.27 Toolchain VS 2019 + W10 SDK 10.0.18362 / Clang 11.0.0 -->
    <!--<WindowsSdkVersion>10.0.18362.0</WindowsSdkVersion> -->
    <!-- <WindowsSdkVersion>10.0.22621.0</WindowsSdkVersion> -->
    <!-- <WindowsSdkVersion>10.0.26100.0</WindowsSdkVersion> Enable if specification would be needed -->
    <!-- <Compiler>VisualStudio2022</Compiler>  -->
  </WindowsPlatform>
</Configuration>

Changes to BuildConfiguration.xml take effect on the next build, but you should regenerate project files after editing it so that the IDE and UBT agree.

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Verifying your toolchain

Before you start a long build, confirm what is actually installed. ViteSetup.bat performs this check for you and prints an [OK] or [FAIL] line for each requirement. To check by hand, look for:

• C:\Program Files\Microsoft Visual Studio\<year>\<edition>\VC\Tools\MSVC\<version>\bin\Hostx64\x64\cl.exe — the MSVC toolsets you have installed are the folder names under VC\Tools\MSVC.
• C:\Program Files (x86)\Windows Kits\10\Include\<version> — the Windows SDKs you have installed.

A second useful checkpoint: watch the build output just before the linking phase begins and confirm which toolchain UBT reports using. Catching a mismatch there is much cheaper than catching it at link time.

See also

• Building from Source
• Build Troubleshooting
• ViteSetup Assistant
• System Requirements