hashicorp/nomad · error

failed to lookup task group %q

Error message

failed to lookup task group %q

What it means

NewAllocRunner validates that the allocation's TaskGroup exists in its Job before constructing the runner. This error means alloc.TaskGroup named a group that alloc.Job does not contain — the allocation and its job definition are inconsistent.

Source

Thrown at client/allocrunner/alloc_runner.go:239

	// partitions is an interface for managing cpuset partitions
	partitions cinterfaces.CPUPartitions

	// widsigner signs workload identities
	widsigner widmgr.IdentitySigner

	// widmgr manages workload identity signatures
	widmgr widmgr.IdentityManager

	// users manages a pool of dynamic workload users
	users dynamic.Pool
}

// NewAllocRunner returns a new allocation runner.
func NewAllocRunner(config *config.AllocRunnerConfig) (interfaces.AllocRunner, error) {
	alloc := config.Alloc
	tg := alloc.Job.LookupTaskGroup(alloc.TaskGroup)
	if tg == nil {
		return nil, fmt.Errorf("failed to lookup task group %q", alloc.TaskGroup)
	}

	ar := &allocRunner{
		id:                       alloc.ID,
		alloc:                    alloc,
		clientConfig:             config.ClientConfig,
		clientBaseLabels:         config.BaseLabels,
		consulServicesHandler:    config.ConsulServices,
		consulProxiesClientFunc:  config.ConsulProxiesFunc,
		vaultClientFunc:          config.VaultFunc,
		tasks:                    make(map[string]*taskrunner.TaskRunner, len(tg.Tasks)),
		waitCh:                   make(chan struct{}),
		destroyCh:                make(chan struct{}),
		shutdownCh:               make(chan struct{}),
		state:                    &state.State{},
		stateDB:                  config.StateDB,
		stateUpdater:             config.StateUpdater,
		taskStateUpdatedCh:       make(chan struct{}, 1),

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Verify alloc.Job and alloc.TaskGroup are both populated before calling NewAllocRunner: ensure the job was fetched/loaded with all task groups (LookupTaskGroup name match is exact)
2. Redeploy the job so a fresh, consistent allocation replaces the corrupt one
3. Inspect the client state store entry for this alloc — if the Job is missing groups, restore from a valid job file (`nomad job revert` or re-run the job)
4. If writing integrations/tests, always set Alloc.TaskGroup to a group name that exists in Alloc.Job.TaskGroups

Example fix

// before
config.Alloc = alloc // Job not populated -> failed to lookup task group
// after
job, err := client.Jobs().Info(alloc.JobID)
if err != nil { return err }
alloc.Job = job
if alloc.Job.LookupTaskGroup(alloc.TaskGroup) == nil {
    return fmt.Errorf("alloc %s references unknown task group %q", alloc.ID, alloc.TaskGroup)
}

// Before constructing an alloc runner, validate consistency
if alloc.Job == nil || alloc.Job.LookupTaskGroup(alloc.TaskGroup) == nil {
  return fmt.Errorf("alloc %s: job missing task group %q", alloc.ID, alloc.TaskGroup)
}

ar, err := NewAllocRunner(cfg)
if err != nil {
  if strings.Contains(err.Error(), "failed to lookup task group") {
    // re-fetch job, restore state, or mark alloc corrupt
  }
  return err
}

When it happens

Trigger: Creating an AllocRunner with a config whose Alloc.Job was not fully populated (e.g. job plan/restore path omitted task groups) or whose TaskGroup name does not match any group in the embedded job; callers include the test suite and internal restore paths.

Common situations: Custom tooling or upgrades injecting/stripping jobs from state (e.g. restoring an alloc whose job spec was truncated); a stale alloc referencing a job version whose group was renamed; hand-crafted alloc structs in automation/scripts.

Related errors

• Reschedule policy has unlimited attempts enabled and a low d
• Lock delay and TTL must be positive
• failed creating runner for task %q: %v
• https_handshake_timeout must be >= 0
• http_max_conns_per_client must be >= 0

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/e310b3f9f7e5f50f. Report an issue: GitHub.