microsoft/playwright · error · Error

Unknown selector engine "${name}"

Error message

Unknown selector engine "${name}"

What it means

Error "Unknown selector engine "${name}"" thrown in microsoft/playwright.

Source

Thrown at packages/injected/src/selectorEvaluator.ts:379

        result = result.concat([...root.querySelectorAll(css)]);
        if (!context.pierceShadow)
          return;
        if ((root as Element).shadowRoot)
          query((root as Element).shadowRoot!);
        for (const element of root.querySelectorAll('*')) {
          if (element.shadowRoot)
            query(element.shadowRoot);
        }
      }
      query(context.scope);
      return result;
    });
  }

  private _getEngine(name: string): SelectorEngine {
    const engine = this._engines.get(name);
    if (!engine)
      throw new Error(`Unknown selector engine "${name}"`);
    return engine;
  }
}

const isEngine: SelectorEngine = {
  matches(element: Element, args: (string | number | Selector)[], context: QueryContext, evaluator: SelectorEvaluator): boolean {
    if (args.length === 0)
      throw new Error(`"is" engine expects non-empty selector list`);
    return args.some(selector => evaluator.matches(element, selector, context));
  },

  query(context: QueryContext, args: (string | number | Selector)[], evaluator: SelectorEvaluator): Element[] {
    if (args.length === 0)
      throw new Error(`"is" engine expects non-empty selector list`);
    let elements: Element[] = [];
    for (const arg of args)
      elements = elements.concat(evaluator.query(context, arg));
    return args.length === 1 ? elements : sortInDOMOrder(elements);

View on GitHub (pinned to c8fc3bf8d3)

When it happens

Trigger: Thrown at packages/injected/src/selectorEvaluator.ts:379 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/playwright@c8fc3bf8d3 (2026-08-12). Data as JSON: /api/errors/bdb0f0914ff5dd4e. Report an issue: GitHub.