DioxusLabs/dioxus · error

Missing wasm-opt

Error message

Missing wasm-opt

What it means

Failure of wasm_opt::get_binary_path when downloads are disabled (CliSettings::prefer_no_downloads), the tool-cache binary is absent, and which::which("wasm-opt") finds nothing on PATH — the optimizer step cannot proceed without a manual install.

Source

Thrown at packages/cli/src/wasm_opt.rs:226

        .ok_or_else(|| anyhow::anyhow!("Failed to get download URL for wasm-opt"))?;

    Ok(download_url.to_string())
}

/// Get the path to the wasm-opt binary, downloading it if necessary
pub async fn get_binary_path() -> anyhow::Result<PathBuf> {
    let install_dir = install_dir();
    let install_path = installed_bin_path(&install_dir);

    if install_path.exists() {
        return Ok(install_path);
    }

    if CliSettings::prefer_no_downloads() {
        if let Ok(existing) = which::which("wasm-opt") {
            return Ok(existing);
        } else {
            return Err(anyhow!("Missing wasm-opt"));
        }
    }

    tracing::info!("Installing wasm-opt");
    install_github(&install_dir).await?;
    tracing::info!("wasm-opt installed from Github");

    Ok(install_path)
}

pub fn installed_location() -> Option<PathBuf> {
    let install_dir = install_dir();
    let install_path = installed_bin_path(&install_dir);

    if install_path.exists() {
        return Some(install_path);
    }

View on GitHub (pinned to 24f6a829df)

Solutions

1. wasm-opt is missing. Install it from the binaryen releases and add it to PATH.

When it happens

Trigger: Thrown at packages/cli/src/wasm_opt.rs:226 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/c26c1c72e20c2178. Report an issue: GitHub.