Unknown platform for wasm-opt installation. Please install w

Error message

Unknown platform for wasm-opt installation. Please install wasm-opt manually from https://github.com/WebAssembly/binaryen/releases and add it to your PATH.

What it means

Terminal guard of the cfg!-based if/else chain in find_latest_wasm_opt_download_url. Fires when the build host's OS/architecture pair is not one of the four prebuilt wasm-opt targets (x86_64/arm64 on windows/linux), so no binaryen release asset can be matched and the download URL cannot be resolved.

Source

Thrown at packages/cli/src/wasm_opt.rs:185

        .get("assets")
        .and_then(|assets| assets.as_array())
        .ok_or_else(|| anyhow::anyhow!("Failed to parse assets"))?;

    // Find the platform identifier based on the current OS and architecture
    let platform = if cfg!(all(target_os = "windows", target_arch = "x86_64")) {
        "x86_64-windows"
    } else if cfg!(all(target_os = "windows", target_arch = "aarch64")) {
        "arm64-windows"
    } else if cfg!(all(target_os = "linux", target_arch = "x86_64")) {
        "x86_64-linux"
    } else if cfg!(all(target_os = "linux", target_arch = "aarch64")) {
        "aarch64-linux"
    } else if cfg!(all(target_os = "macos", target_arch = "x86_64")) {
        "x86_64-macos"
    } else if cfg!(all(target_os = "macos", target_arch = "aarch64")) {
        "arm64-macos"
    } else {
        bail!(
            "Unknown platform for wasm-opt installation. Please install wasm-opt manually from https://github.com/WebAssembly/binaryen/releases and add it to your PATH."
        );
    };

    // Find the first asset with a name that contains the platform string
    let asset = assets
        .iter()
        .find(|asset| {
            asset
                .get("name")
                .and_then(|name| name.as_str())
                .is_some_and(|name| name.contains(platform) && !name.ends_with("sha256"))
        })
        .with_context(|| anyhow!(
            "No suitable wasm-opt binary found for platform: {}. Please install wasm-opt manually from https://github.com/WebAssembly/binaryen/releases and add it to your PATH.",
            platform
        ))?;

View on GitHub (pinned to 24f6a829df)

Solutions

No wasm-opt build exists for this platform. Install wasm-opt manually from the binaryen releases and add it to PATH.

Defensive patterns

Strategy: fallback

When it happens

Trigger: Thrown at packages/cli/src/wasm_opt.rs:185 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of DioxusLabs/dioxus@24f6a829df (2026-08-23). Data as JSON: /api/errors/93053c705dc94fd7. Report an issue: GitHub.