GoogleChrome/lighthouse · error · Error

No timespan in progress

Error message

No timespan in progress

What it means

State-machine guard in UserFlow.endTimespan(). Requires currentTimespan to be set. Fires when endTimespan() is called without a prior startTimespan(), or when endTimespan() is called twice (the second call finds currentTimespan already cleared to undefined at line 213).

Source

Thrown at core/user-flow.js:208

  /**
   * @param {LH.UserFlow.StepFlags} [flags]
   */
  async startTimespan(flags) {
    if (this.currentTimespan) throw new Error('Timespan already in progress');
    if (this.currentNavigation) throw new Error('Navigation already in progress');

    const nextFlags = this._getNextFlags(flags);

    const timespan = await startTimespanGather(this._page, {
      config: this._options?.config,
      flags: nextFlags,
    });
    this.currentTimespan = {timespan, flags: nextFlags};
  }

  async endTimespan() {
    if (!this.currentTimespan) throw new Error('No timespan in progress');
    if (this.currentNavigation) throw new Error('Navigation already in progress');

    const {timespan, flags} = this.currentTimespan;
    const gatherResult = await timespan.endTimespanGather();
    this.currentTimespan = undefined;

    this._addGatherStep(gatherResult, flags);
  }

  /**
   * @param {LH.UserFlow.StepFlags} [flags]
   */
  async snapshot(flags) {
    if (this.currentTimespan) throw new Error('Timespan already in progress');
    if (this.currentNavigation) throw new Error('Navigation already in progress');

    const nextFlags = this._getNextFlags(flags);

View on GitHub (pinned to 9515cd4e58)

Solutions

1. Ensure startTimespan() was called before endTimespan()
2. Check flow.currentTimespan is set before calling endTimespan()
3. Do not call endTimespan() twice — guard with a currentTimespan check

Example fix

// before — endTimespan without startTimespan
await flow.endTimespan(); // throws

// after — start timespan first
await flow.startTimespan();
// ... interactions ...
await flow.endTimespan();

if (!flow.currentTimespan) {
  console.error('No timespan in progress — did you call startTimespan()?');
  return;
}
await flow.endTimespan();

/** @param {UserFlow} flow @returns {boolean} */
function canEndTimespan(flow) {
  return flow.currentTimespan != null && flow.currentNavigation == null;
}

When it happens

Trigger: Calling flow.endTimespan() when flow.currentTimespan is undefined. Happens when startTimespan() was never called, or after endTimespan() already completed and cleared the state.

Common situations: Forgot to call startTimespan() first. Double-calling endTimespan(). Calling endTimespan() by mistake instead of endNavigation(). Exception in a try/finally that caused endTimespan to run after it was already ended.

Related errors

• Timespan already in progress
• No navigation in progress
• Navigation already in progress
• unexpected response: ${response.statusCode} ${response.statu
• No lantern metrics available, did you run run-on-all-assets.

AI-assisted analysis of GoogleChrome/lighthouse@9515cd4e58 (2026-08-13). Data as JSON: /api/errors/f41c66a6c263a7c1. Report an issue: GitHub.