denoland/deno · error · TypeError

Passing 'args' in options is not allowed when args are passe

Error message

Passing 'args' in options is not allowed when args are passed as a separate argument

What it means

Deno.spawn(command, argsOrOptions, maybeOptions) (unstable API) detects two conflicting ways to specify arguments: a positional args array plus an args property inside the options object. When both are present it throws a TypeError, because it cannot know which list you intended. Pass args either positionally or in options — never both.

Source

Thrown at ext/process/40_process.js:834

  }

  spawn() {
    const options = {
      __proto__: null,
      ...(this.#options ?? {}),
      stdout: this.#options?.stdout ?? "inherit",
      stderr: this.#options?.stderr ?? "inherit",
      stdin: this.#options?.stdin ?? "inherit",
    };
    return spawnChild(this.#command, options);
  }
}

function spawn(command, argsOrOptions, maybeOptions) {
  if (ArrayIsArray(argsOrOptions)) {
    const options = maybeOptions ?? {};
    if (options.args !== undefined) {
      throw new TypeError(
        "Passing 'args' in options is not allowed when args are passed as a separate argument",
      );
    }
    return new Command(command, { ...options, args: argsOrOptions }).spawn();
  }
  return new Command(command, argsOrOptions).spawn();
}

function spawnAndWait(command, argsOrOptions, maybeOptions) {
  if (ArrayIsArray(argsOrOptions)) {
    const options = maybeOptions ?? {};
    if (options.args !== undefined) {
      throw new TypeError(
        "Passing 'args' in options is not allowed when args are passed as a separate argument",
      );
    }
    return new Command(command, { ...options, args: argsOrOptions }).output();
  }

View on GitHub (pinned to 9ad36f7a2c)

Solutions

1. Delete the args property from the options object when args are passed as the second parameter
2. Or pass everything in options: Deno.spawn(cmd, { args: [...] }) with no second array
3. In adapter layers, strip options.args before forwarding when you also forward a positional array

Example fix

// before
Deno.spawn("git", ["status"], { args: ["status"], stdout: "piped" }); // TypeError

// after
Deno.spawn("git", ["status"], { stdout: "piped" });

const { args: _omit, ...optsSansArgs } = options ?? {};
Deno.spawn(cmd, argArray, optsSansArgs); // safe: no duplicate args
// or: Deno.spawn(cmd, { ...options, args: argArray })

function hasConflictingArgs(args: unknown, options: { args?: unknown } | undefined): boolean {
  return Array.isArray(args) && options?.args !== undefined;
}

When it happens

Trigger: Deno.spawn("git", ["status"], { args: ["log"], stdout: "piped" }) — second argument is an Array and the third (options) also defines args. Also triggered by helpers that merge user options containing args into a call that already passes them positionally.

Common situations: Spreading a default options object that already carries args; adapters from Node's child_process.spawn(command, args, options) whose options type includes args; refactors that move args from options to positional without deleting the old property.

Related errors

• Cannot get 'stdout': 'stdout' is not piped
• Cannot get 'stderr': 'stderr' is not piped
• Illegal constructor
• Piped stdin is not supported for this function, use 'Deno.Co
• ERR_INVALID_ARG_VALUE

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/33379b3e88185184. Report an issue: GitHub.