denoland/deno · error

--output is not supported with HTML entrypoints; use…

Error message

--output is not supported with HTML entrypoints; use --outdir

What it means

`deno bundle` rejects the combination of `--output` (a single output path) with HTML entrypoints. HTML bundling emits multiple files into a directory (JS with content hash, `.js.map`, patched HTML), so a single output path cannot represent the result; the error tells you to use `--outdir` instead.

Solutions

1. Replace `--output` with `--outdir`: `deno bundle --outdir=dist index.html`
2. If a single JS file is genuinely required, bundle the script module directly and keep HTML out of the entrypoints

Example fix

# before
deno bundle --output=app.js index.html

# after
deno bundle --outdir=dist index.html

// Wrapper: reject --output when any entry ends with .html
const entries = Deno.args.filter((a) => !a.startsWith("-"));
if (
  entries.some((e) => e.endsWith(".html")) &&
  Deno.args.some((a) => a.startsWith("--output") || a === "-o")
) {
  throw new Error("use --outdir, not --output, when bundling HTML");
}

When it happens

Trigger: `deno bundle --output=app.js index.html` — any run with at least one HTML entrypoint plus the `--output` flag.

Common situations: Build scripts ported from JS bundling that hard-code `--output`; muscle memory from esbuild's `--outfile` flag.

Related errors

• --outdir is required when bundling HTML entrypoints
• failed to locate output for HTML entry
• Deno.bundle() is not available in compiled binaries (`deno…
• Entry point must be a file
• ERR_WORKER_INVALID_EXEC_ARGV

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/40eeb22375dbc912. Report an issue: GitHub.

Appendix: source

Thrown at cli/tools/bundle/mod.rs:153

    let graph = plugin_handler.module_graph_container.graph();
    let mut fully_resolved_roots = IndexSet::with_capacity(graph.roots.len());
    for root in &graph.roots {
      fully_resolved_roots.insert(graph.resolve(root).clone());
    }
    *plugin_handler.resolved_roots.write() = Arc::new(fully_resolved_roots);

    Ok(BundlerInput::Entrypoints(
      roots.into_iter().map(|e| ("".into(), e.into())).collect(),
    ))
  } else {
    // require an outdir when any HTML is present
    if bundle_flags.output_dir.is_none() {
      return Err(deno_core::anyhow::anyhow!(
        "--outdir is required when bundling HTML entrypoints",
      ));
    }
    if bundle_flags.output_path.is_some() {
      return Err(deno_core::anyhow::anyhow!(
        "--output is not supported with HTML entrypoints; use --outdir",
      ));
    }

    // Prepare HTML pages and temp entry modules
    let mut html_pages = Vec::new();
    let mut to_cache_urls = Vec::new();
    let mut entries: Vec<(String, String)> = Vec::new();
    let virtual_modules = Arc::new(VirtualModules::new());

    for html_path in &html_paths {
      let entry = html::load_html_entrypoint(
        init_cwd,
        html_path,
        plugin_handler
          .is_runtime_api
          .then_some(&plugin_handler.permissions),
      )?;

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