hashicorp/nomad · warning

cron is deprecated and may be removed in a future release. U

Error message

cron is deprecated and may be removed in a future release. Use crons instead

What it means

Job.Validate emits a deprecation warning-style error when a periodic job uses the legacy `cron` field (Periodic.Spec) instead of the newer `crons` list (Periodic.Specs). The message tells the user that `cron` is deprecated and may be removed in a future release.

Source

Thrown at nomad/structs/structs.go:4987

			hasAutoPromote = hasAutoPromote || u.AutoPromote

			// Having no canaries implies auto-promotion since there are no canaries to promote.
			allAutoPromote = allAutoPromote && (u.Canary == 0 || u.AutoPromote)
		}
	}

	// check if we have services with no shutdown delay set
	mErr.Errors = append(mErr.Errors, j.generateServiceShutdownDelayWarnings()...)

	// Check AutoPromote, should be all or none
	if hasAutoPromote && !allAutoPromote {
		err := fmt.Errorf("auto_promote must be true for all groups to enable automatic promotion")
		mErr.Errors = append(mErr.Errors, err)
	}

	// cron -> crons
	if j.Periodic != nil && j.Periodic.Spec != "" {
		err := fmt.Errorf("cron is deprecated and may be removed in a future release. Use crons instead")
		mErr.Errors = append(mErr.Errors, err)
	}

	return mErr.ErrorOrNil()
}

// LookupTaskGroup finds a task group by name
func (j *Job) LookupTaskGroup(name string) *TaskGroup {
	if j == nil {
		return nil
	}
	for _, tg := range j.TaskGroups {
		if tg.Name == name {
			return tg
		}
	}
	return nil
}

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Replace `cron = "<expr>"` with `crons = ["<expr>"]` in the periodic block.
2. If multiple schedules are needed, list them all under crons.
3. Grep job templates/repos for `cron =` to remove remaining legacy usages.

Example fix

// before
periodic {
  enabled = true
  cron = "0 * * * *"
}
// after
periodic {
  enabled = true
  crons = ["0 * * * *"]
}

if job.Periodic != nil && job.Periodic.Spec != "" {
    return fmt.Errorf("use crons = [...] instead of deprecated cron field")
}

When it happens

Trigger: Submitting a job whose `periodic` block sets `cron = "..."` (single spec field) rather than `crons = [...]`. Detected via j.Periodic != nil && j.Periodic.Spec != "".

Common situations: Old job files carried forward from pre-crons Nomad versions; tutorials/examples referencing the legacy field; scripts generating periodic jobs from templates that still use `cron`.

Related errors

• Multiple service providers used: task group services must us
• MaxClientDisconnect is deprecated and ignored in favor of Di
• StopAfterClientDisconnect is deprecated and ignored favor of
• PreventRescheduleOnLost is deprecated and ignored in favor o
• must specify cron block

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/021cbd5b8f024020. Report an issue: GitHub.