jamiepine/voicebox · warning · HTTPException

Downloadable CUDA backend releases are currently only publis

Error message

Downloadable CUDA backend releases are currently only published for Windows.

What it means

HTTP 409 raised by POST /backend/download-cuda when cuda.get_cuda_download_unsupported_reason() returns a non-None string. That function returns the constant 'Downloadable CUDA backend releases are currently only published for Windows.' on every platform where sys.platform != 'win32' (i.e. Linux and macOS). The prebuilt CUDA backend archive is only published for Windows releases, so the download endpoint refuses on other OSes.

Source

Thrown at backend/routes/cuda.py:31

logger = logging.getLogger(__name__)


@router.get("/backend/cuda-status")
async def get_cuda_status():
    """Get CUDA backend download/availability status."""
    from ..services import cuda

    return cuda.get_cuda_status()


@router.post("/backend/download-cuda")
async def download_cuda_backend():
    """Download the CUDA backend binary."""
    from ..services import cuda

    unsupported_reason = cuda.get_cuda_download_unsupported_reason()
    if unsupported_reason:
        raise HTTPException(status_code=409, detail=unsupported_reason)

    if cuda.get_cuda_binary_path() is not None:
        raise HTTPException(status_code=409, detail="CUDA backend already downloaded")

    progress_manager = get_progress_manager()
    existing = progress_manager.get_progress(cuda.PROGRESS_KEY)
    if existing and existing.get("status") == "downloading":
        raise HTTPException(status_code=409, detail="CUDA backend download already in progress")

    async def _download():
        try:
            await cuda.download_cuda_binary()
        except Exception as e:
            logger.error("CUDA download failed: %s", e)

    create_background_task(_download())
    return {"message": "CUDA backend download started", "progress_key": "cuda-backend"}

View on GitHub (pinned to 51f49dea19)

Solutions

1. Run the download flow only on Windows; on Linux/macOS use a CPU backend or build CUDA support locally.
2. Gate the UI 'Download CUDA' button on the status payload's download_supported flag (GET /backend/cuda).
3. If CUDA is required on Linux, provision a GPU node with the CUDA toolkit and run the CUDA server binary directly rather than via this endpoint.

Example fix

// before
await fetch('/backend/download-cuda', { method: 'POST' });
// after
const status = await fetch('/backend/cuda').then(r => r.json());
if (!status.download_supported) { alert(status.unsupported_reason); return; }
await fetch('/backend/download-cuda', { method: 'POST' });

const status = await fetch('/backend/cuda').then(r => r.json());
if (!status.download_supported) throw new Error(status.unsupported_reason);

function isWindowsDownloadSupported(s): s is { download_supported: true } { return s?.download_supported === true; }

const r = await fetch('/backend/download-cuda', { method:'POST' });
if (r.status === 409) { const { detail } = await r.json(); /* platform / already downloaded / in progress */ }

When it happens

Trigger: Calling POST /backend/download-cuda from a Linux or macOS host (or any non-win32 sys.platform).

Common situations: Running the app on Linux/macOS and clicking 'Download CUDA backend' in the UI; a cross-platform deployment that assumes the CUDA backend is universally downloadable; Docker container on a Linux image.

Related errors

• CUDA backend already downloaded
• CUDA backend download already in progress
• Cannot delete CUDA backend while it is active. Switch to CPU
• No CUDA backend found to delete
• HTTP error! status: ${response.status}

AI-assisted analysis of jamiepine/voicebox@51f49dea19 (2026-08-12). Data as JSON: /api/errors/5440be8c91146b98. Report an issue: GitHub.