microsoft/playwright · error · Error

Callback must be provided to timer calls

Error message

Callback must be provided to timer calls

What it means

Error "Callback must be provided to timer calls" thrown in microsoft/playwright.

Source

Thrown at packages/injected/src/clock.ts:302

  private async _innerFastForwardTo(to: Ticks) {
    if (to < this._now.ticks)
      throw new Error('Cannot fast-forward to the past');
    for (const timer of this._timers.values()) {
      if (to > timer.callAt)
        timer.callAt = to;
    }
    await this._runTo(to);
  }

  addTimer(options: { func: TimerHandler, type: TimerType, delay?: number | string, args?: any[] }): number {
    this._replayLogOnce();

    if (options.type === TimerType.AnimationFrame && !options.func)
      throw new Error('Callback must be provided to requestAnimationFrame calls');
    if (options.type === TimerType.IdleCallback && !options.func)
      throw new Error('Callback must be provided to requestIdleCallback calls');
    if ([TimerType.Timeout, TimerType.Interval].includes(options.type) && !options.func && options.delay === undefined)
      throw new Error('Callback must be provided to timer calls');

    let delay = options.delay ? +options.delay : 0;
    if (!Number.isFinite(delay))
      delay = 0;
    delay = delay > maxTimeout ? 1 : delay;
    delay = Math.max(0, delay);

    const timer: Timer = {
      type: options.type,
      func: options.func,
      args: options.args || [],
      delay,
      callAt: shiftTicks(this._now.ticks, (delay || (this._duringTick ? 1 : 0))),
      createdAt: this._now.ticks,
      id: this._uniqueTimerId++,
      error: new Error(),
    };
    this._timers.set(timer.id, timer);

View on GitHub (pinned to c8fc3bf8d3)

When it happens

Trigger: Thrown at packages/injected/src/clock.ts:302 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/df969d91eb2de631. Report an issue: GitHub.