LykosAI/StabilityMatrix · error · MissingPrerequisiteException

Could not find Visual Studio 2022 Build Tools. Please…

Error message

Could not find Visual Studio 2022 Build Tools. Please install them from the link below.

What it means

When no prebuilt wheels are available, InstallSageAttentionStep falls back to compiling from source, which requires Visual Studio 2022 Build Tools. If prerequisiteHelper.IsVcBuildToolsInstalled is false, MissingPrerequisiteException is thrown with the download link.

Solutions

Install VS2022 Build Tools from https://aka.ms/vs/17/release/vs_BuildTools.exe (include C++ workload)
Rerun the install step after Build Tools are present
Use a Python version for which prebuilt SageAttention wheels exist to avoid compilation

Defensive patterns

Strategy: validation

Validate before calling

if (!prerequisiteHelper.IsVcBuildToolsInstalled)
    await installer.LaunchVsBuildToolsSetup();

Try / catch

try { await step.ExecuteAsync(progress); } catch (MissingPrerequisiteException ex) { ui.ShowPrerequisiteDialog(ex.Name, ex.Message, ex.Url); }

Prevention

Run a prerequisite check (Build Tools, CUDA) before source builds
Prefer Python versions with prebuilt wheels to avoid compilation
Prompt users to install Build Tools early in setup

When it happens

Trigger: ExecuteAsync on Windows with no matching prebuilt wheels and no VS2022 Build Tools installed, so compilation prerequisites are missing.

Common situations: Fresh Windows installs without development tools; users declined Build Tools during earlier setups; CUDA/torch source builds triggered by unusual Python versions lacking wheels.

Understand the failure class

Background: "not installed", "pip install", "required for": how missing-dependency errors surface across open-source libraries — this error's family across 34 libraries.

Related errors

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/4fabdce41ec8fc49. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Core/Models/PackageModification/InstallSageAttentionStep.cs:142

        var pipArgs = new PipInstallArgs("triton-windows");

        if (!string.IsNullOrWhiteSpace(sageWheelUrl))
        {
            pipArgs = pipArgs.AddArg(sageWheelUrl);

            progress?.Report(
                new ProgressReport(-1f, message: "Installing Triton & SageAttention", isIndeterminate: true)
            );

            await venvRunner.PipInstall(pipArgs, progress.AsProcessOutputHandler()).ConfigureAwait(false);

            return;
        }

        // no wheels, gotta build
        if (!prerequisiteHelper.IsVcBuildToolsInstalled)
        {
            throw new MissingPrerequisiteException(
                "Visual Studio 2022 Build Tools",
                "Could not find Visual Studio 2022 Build Tools. Please install them from the link below.",
                "https://aka.ms/vs/17/release/vs_BuildTools.exe"
            );
        }

        var nvccPath = await Utilities.WhichAsync("nvcc").ConfigureAwait(false);
        if (string.IsNullOrWhiteSpace(nvccPath))
        {
            var cuda126ExpectedPath = new DirectoryPath(
                @"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.6\bin"
            );
            var cuda128ExpectedPath = new DirectoryPath(
                @"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v12.8\bin"
            );

            if (!cuda126ExpectedPath.Exists && !cuda128ExpectedPath.Exists)
            {

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