Job task group %s has count %d. Count cannot exceed 1 with s

Error message

Job task group %s has count %d. Count cannot exceed 1 with system scheduler

What it means

Job.Validate() rejects system job groups with count greater than 1: 'Job task group %s has count %d. Count cannot exceed 1 with system scheduler'. System jobs run one allocation per eligible node, so the count field is ignored/meaningless beyond 1.

Source

Thrown at nomad/structs/structs.go:4841

	// Check for duplicate task groups
	taskGroups := make(map[string]int)
	for idx, tg := range j.TaskGroups {
		if tg.Name == "" {
			mErr.Errors = append(mErr.Errors, fmt.Errorf("Job task group %d missing name", idx+1))
		} else if existing, ok := taskGroups[tg.Name]; ok {
			mErr.Errors = append(mErr.Errors, fmt.Errorf("Job task group %d redefines '%s' from group %d", idx+1, tg.Name, existing+1))
		} else {
			taskGroups[tg.Name] = idx
		}

		if tg.ShutdownDelay != nil && *tg.ShutdownDelay < 0 {
			mErr.Errors = append(mErr.Errors, errors.New("ShutdownDelay must be a positive value"))
		}

		if j.Type == "system" && tg.Count > 1 {
			mErr.Errors = append(mErr.Errors,
				fmt.Errorf("Job task group %s has count %d. Count cannot exceed 1 with system scheduler",
					tg.Name, tg.Count))
		}
	}

	// Validate the task group
	for _, tg := range j.TaskGroups {
		if err := tg.Validate(j); err != nil {
			outer := fmt.Errorf("Task group %s validation failed: %v", tg.Name, err)
			mErr.Errors = append(mErr.Errors, outer)
		}
	}

	// Validate periodic is only used with batch or sysbatch jobs.
	if j.IsPeriodic() && j.Periodic.Enabled {
		if j.Type != JobTypeBatch && j.Type != JobTypeSysBatch {
			mErr.Errors = append(mErr.Errors, fmt.Errorf(
				"Periodic can only be used with %q or %q scheduler", JobTypeBatch, JobTypeSysBatch,
			))

View on GitHub (pinned to 482b49bf1a)

Solutions

Remove the count field from the system job's group (or set it to 1/leave default)
Keep count > 1 only on service or batch jobs
If scaling across nodes is the goal, remember system jobs automatically run on every eligible node
Run 'nomad job validate' before submission

Example fix

// before
job "sys" {
  type = "system"
  group "agent" { count = 3 }
}
// after
job "sys" {
  type = "system"
  group "agent" {}
}

Defensive patterns

Strategy: validation

Validate before calling

if job.Type == "system" {
    for _, tg := range job.TaskGroups {
        if tg.Count > 1 {
            return fmt.Errorf("group %s: count must be <= 1 for system jobs", tg.Name)
        }
    }
}
return nil

Try / catch

if err := job.Validate(); err != nil {
    if strings.Contains(err.Error(), "Count cannot exceed 1 with system scheduler") {
        return ErrSystemJobCount
    }
    return err
}

Prevention

Omit count entirely on system job groups
Use distinct job templates for system vs service types
Warn in CI when type=system and any count > 1

When it happens

Trigger: Submitting a job with type = "system" where any TaskGroup has Count > 1, typically because the group was copied from a service job or Count was set explicitly.

Common situations: Converting a service job to system without removing count, provisioning tools that always emit count = N, misunderstanding that system scheduler derives count from node eligibility.

Related errors

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/66d1bab1a95b12af. Report an issue: GitHub.