What causes "Job was cancelled" in windmill-labs/windmill?

Wrap the runWithProgress call in try/catch and treat Error with message 'Job was cancelled' as an expected, non-alerting outcome

windmill-labs/windmill · warning · Error

Job was cancelled

Error message

Job was cancelled

What it means

JobManager.runWithProgress polls a Windmill job until completion. On each poll tick it checks the AbortController created for the run; if the job was cancelled (via cancel(jobId) or cancelAll(), which call controller.abort()), the next poll throws Error('Job was cancelled') and the promise rejects.

Source

Thrown at frontend/src/lib/services/JobManager.ts:86

		} = options

		const controller = new AbortController()
		const jobId = await jobRunner()

		this.activeJobs.set(jobId, {
			controller,
			startTime: Date.now()
		})

		try {
			onProgress?.({ status: 'running' })

			let finalResult: T | undefined = undefined

			await tryEvery({
				tryCode: async () => {
					if (controller.signal.aborted) {
						throw new Error('Job was cancelled')
					}

					let jobResult
					try {
						jobResult = await JobService.getCompletedJob({
							workspace,
							id: jobId
						})
					} catch (error) {
						throw error
					}

					const success = !!jobResult.success
					const status: JobStatus = {
						status: success ? 'success' : 'failure',
						result: jobResult.result,
						error: success ? undefined : (jobResult.result as any)?.error?.message || 'Job failed'
					}

View on GitHub (pinned to e474e8803c)

Solutions

Wrap the runWithProgress call in try/catch and treat Error with message 'Job was cancelled' as an expected, non-alerting outcome
Avoid calling cancelAll()/cancel() on teardown if you still need the result, or await the promise before teardown
Check controller state / isActive(jobId) before relying on the result

Example fix

// before
const result = await jobManager.runWithProgress(runJob, opts)
// after
try {
  const result = await jobManager.runWithProgress(runJob, opts)
} catch (err) {
  if (err instanceof Error && err.message === 'Job was cancelled') return // expected on teardown
  throw err
}

Defensive patterns

Strategy: try-catch

Validate before calling

// before awaiting, ensure no cancellation is pending
if (jobManager.isActive(jobId) === false || controller?.signal.aborted) {
  return // skip the run
}

Type guard

function isCancellationError(err: unknown): err is Error {
  return err instanceof Error && err.message === 'Job was cancelled'
}

Try / catch

try {
  const result = await jobManager.runWithProgress(runJob, opts)
} catch (err) {
  if (isCancellationError(err)) {
    return null // user-initiated or teardown cancellation: handle silently
  }
  throw err
}

Prevention

Treat 'Job was cancelled' as an expected control-flow signal, not a failure to report
Cancel jobs deliberately on component teardown and handle the resulting rejection
Avoid calling cancelAll() when individual runs' results are still needed
Track jobIds you cancel so you can correlate the rejection

When it happens

Trigger: Calling runWithProgress, then invoking jobManager.cancel(jobId) or cancelAll() (e.g. component teardown, navigation away, user pressing a cancel button) while the polling loop is still running; or the abort signal already aborted when a poll tick fires.

Common situations: Svelte component destroyed mid-run without awaiting; user navigating away from an AI-generation/preview panel; a timeout elsewhere aborting all jobs; race where abort happens between job start and first poll.

Related errors

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/6565b2922bbfe353. Report an issue: GitHub.