DioxusLabs/dioxus · error

input_path should be valid utf8

Error message

input_path should be valid utf8

What it means

Before invoking wasm-bindgen, dx stringifies the output directory with Path::to_str(); on this platform paths can contain non-UTF-8 bytes, to_str() returns None, and the expect panics. The message says input_path but line 147 converts out_dir - a copy-paste in the panic text.

Source

Thrown at packages/cli/src/wasm_bindgen.rs:147

            args.push("--remove-producers-section");
        }

        if self.keep_lld_exports {
            args.push("--keep-lld-exports");
        }

        // Out name
        args.push("--out-name");
        args.push(&self.out_name);

        // wbg generates typescript bindnings by default - we don't want those
        args.push("--no-typescript");

        // Out dir
        let out_dir = self
            .out_dir
            .to_str()
            .expect("input_path should be valid utf8");

        args.push("--out-dir");
        args.push(out_dir);

        // Input path
        let input_path = self
            .input_path
            .to_str()
            .expect("input_path should be valid utf8");
        args.push(input_path);

        tracing::debug!("wasm-bindgen: {:#?}", args);

        // Run bindgen
        let output = Command::new(binary).args(args).output().await?;

        // Check for errors
        if !output.stderr.is_empty() {

View on GitHub (pinned to 393d190a80)

Solutions

1. Move or clone the project to a purely ASCII, UTF-8-safe path
2. Point CARGO_TARGET_DIR at a short ASCII path (e.g. /tmp/dx-target or C:\\dx\\target)
3. Rename the offending parent directory so the full path becomes valid UTF-8

fn assert_utf8_path(p: &std::path::Path) -> anyhow::Result<&str> {
    p.to_str().ok_or_else(|| anyhow::anyhow!("path is not valid UTF-8: {:?}", p))
}

fn is_utf8_path(p: &std::path::Path) -> bool { p.to_str().is_some() }

When it happens

Trigger: dx serve/dx build for web where the target/output directory path contains bytes invalid as UTF-8 - typically Windows or macOS folders or usernames with legacy encodings (latin-1, shift-jis).

Common situations: Non-ASCII usernames with broken normalization; projects moved from old systems with differently encoded directory names; mounted volumes exposing byte-encoded names.

Related errors

• Failed to convert wasm bindgen output path to string
• expected URL to be UTF-8 encoded
• Failed to read index.html from public directory
• failed to expand ifunc table
• Could not find export

AI-assisted analysis of DioxusLabs/dioxus@393d190a80 (2026-08-16). Data as JSON: /api/errors/ae9cb002ca1750db. Report an issue: GitHub.