DioxusLabs/dioxus · error

failed to create output dir

Error message

failed to create output dir

What it means

The wasm-split CLI's `split` subcommand deletes any existing directory at `out_dir` (ignoring errors) and then recreates it with `std::fs::create_dir_all(...).expect("failed to create output dir")`. If the OS refuses to create the directory, the process panics with exit code 101 before any wasm work happens. This is an environment failure (permissions, disk, path collision), not a problem with the wasm binaries being split.

Source

Thrown at packages/wasm-split/wasm-split-cli/src/main.rs:46

#[derive(Parser)]
struct SplitArgs {
    /// The wasm module emitted by rustc
    original: PathBuf,

    /// The wasm module emitted by wasm-bindgen
    bindgened: PathBuf,

    /// The output *directory* to write the split wasm files to
    out_dir: PathBuf,
}

fn split(args: SplitArgs) {
    let original = std::fs::read(&args.original).expect("failed to read input file");
    let bindgened = std::fs::read(&args.bindgened).expect("failed to read input file");

    _ = std::fs::remove_dir_all(&args.out_dir);
    std::fs::create_dir_all(&args.out_dir).expect("failed to create output dir");

    tracing::info!("Building split module");

    let module = wasm_split_cli::Splitter::new(&original, &bindgened).unwrap();

    let mut chunks = module.emit().unwrap();

    // Write out the main module
    tracing::info!(
        "Writing main module to {}",
        args.out_dir.join("main.wasm").display()
    );
    std::fs::write(args.out_dir.join("main.wasm"), &chunks.main.bytes).unwrap();

    // Write the js module
    std::fs::write(
        args.out_dir.join("__wasm_split.js"),
        emit_js(&chunks.chunks, &chunks.modules),

View on GitHub (pinned to 393d190a80)

Solutions

1. Check whether a file (not a directory) occupies the out_dir path (`ls -la <out_dir>`) and remove or rename it
2. Verify the parent directory is writable (`chmod u+w` on the parent, or choose another location)
3. Pass an absolute out_dir path so the location does not depend on the invoker's cwd
4. Free disk space or raise the quota, then re-run the split command

Example fix

# before: dist exists as a file, split panics with "failed to create output dir"
wasm-split-cli split app.wasm bg.wasm dist
# after: clear the collision and use an absolute path
rm -f dist && wasm-split-cli split app.wasm bg.wasm "$(pwd)/dist"

OUT_DIR="$(pwd)/dist"
if [ -e "$OUT_DIR" ] && [ ! -d "$OUT_DIR" ]; then echo "out_dir exists and is not a directory"; exit 1; fi
mkdir -p "$OUT_DIR" 2>/dev/null || { echo "cannot create out_dir"; exit 1; }
[ -w "$OUT_DIR" ] || { echo "out_dir is not writable"; exit 1; }
wasm-split-cli split app.wasm bg.wasm "$OUT_DIR"

if ! wasm-split-cli split app.wasm bg.wasm "$OUT_DIR"; then echo "split failed (exit $?) - check the panic message for the OS error" >&2; exit 1; fi

When it happens

Trigger: Running `wasm-split-cli split <original> <bindgened> <out_dir>` where a regular file already occupies the out_dir path (remove_dir_all silently fails on files, so create_dir_all hits EEXIST/ENOTDIR); the parent directory is read-only or lacks write permission for the current user; the path is on a full disk, an unwritable mount, or exceeds filesystem path-length limits.

Common situations: CI containers running as non-root with a restricted workspace; passing `dist` as out_dir when `dist` already exists as a build artifact file; a relative out_dir resolved from an unexpected working directory when the binary is invoked by a script; Docker disk quota exhausted.

Related errors

• failed to write chunk
• Failed to create args directory for rustc wrapper
• failed to expand ifunc table
• Could not find export
• failed to read input file

AI-assisted analysis of DioxusLabs/dioxus@393d190a80 (2026-08-16). Data as JSON: /api/errors/c4db7f75715de3b9. Report an issue: GitHub.