dgraph-io/dgraph · error

task failed

Error message

task failed

What it means

After enqueuing, Enqueue polls the task log for up to ~3 seconds and returns immediately with 'task failed' if the task's metadata transitions to TaskStatusFailed. This is the early-failure signal from the task worker — the task started and failed quickly (within the 3s window).

Source

Thrown at worker/queue.go:152

	}

	id, err := t.enqueue(req)
	if err != nil {
		return 0, err
	}

	// Wait for upto 3 seconds to check for errors.
	for range 3 {
		time.Sleep(time.Second)

		t.logMu.Lock()
		meta := TaskMeta(t.log.Get(id))
		t.logMu.Unlock()

		// Early return
		switch meta.Status() {
		case TaskStatusFailed:
			return 0, fmt.Errorf("task failed")
		case TaskStatusSuccess:
			return id, nil
		}
	}

	return id, nil
}

// enqueue adds a new task to the queue. This must be of type:
// - *pb.BackupRequest
// - *pb.ExportRequest
func (t *tasks) enqueue(req interface{}) (uint64, error) {
	var kind TaskKind
	switch req.(type) {
	case *pb.BackupRequest:
		kind = TaskKindBackup
	case *pb.ExportRequest:
		kind = TaskKindExport

View on GitHub (pinned to 759e242be6)

Solutions

1. Read the Alpha logs around the task ID for the underlying task error (this error itself carries no detail)
2. Fix the task destination/permissions (e.g. S3 credentials, bucket, path) and re-enqueue
3. Validate the request (BackupRequest/ExportRequest fields, target format) before enqueueing
4. Instead of relying on Enqueue's 3s window, poll TaskStatus with the returned task ID for the authoritative status

Example fix

// before
id, err := tasks.Enqueue(req)
if err != nil { return err } // "task failed" with no detail
// after
id, err := tasks.Enqueue(req)
if err != nil {
    return fmt.Errorf("task %d failed, see alpha logs for cause: %w", id, err)
}
// then poll task status for detailed progress
meta, err := tasks.Get(id)

// Validate the destination before enqueueing
classic := func() error {
    if bucket == "" || accessKey == "" { return fmt.Errorf("incomplete backup destination") }
    return nil
}()

id, err := tasks.Enqueue(req)
if err != nil && strings.Contains(err.Error(), "task failed") {
    // fetch real cause from alpha logs / task status
    meta, _ := tasks.Get(id)
    return fmt.Errorf("task %d failed: status=%v", id, meta.Status())
}

When it happens

Trigger: Enqueue a backup or export request whose execution fails almost immediately (e.g. handler returns an error right away) so the polling loop observes TaskStatusFailed and returns fmt.Errorf("task failed").

Common situations: Backups failing instantly due to bad S3/destination credentials; export failing on an invalid or inaccessible target path; permission errors on the storage backend; malformed request parameters rejected by the task handler at start.

Related errors

• too many pending tasks, please try again later
• task does not exist or has expired
• illegal rune found "%c", expecting {
• JSON map is followed by illegal rune "%c"
• Malformed JSON

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/411b9bae02708447. Report an issue: GitHub.