hashicorp/nomad · error

SignalTask is not supported by this driver

Error message

SignalTask is not supported by this driver

What it means

Driver capability stub: the task's driver embeds DriverSignalTaskNotSupported, so it cannot honor SignalTask. The error comes from the default implementation that drivers opt into when signaling tasks is impossible.

Source

Thrown at plugins/drivers/driver.go:123

	// terminal size channel
	ResizeCh <-chan TerminalSize
}

// DriverNetworkManager is the interface with exposes function for creating a
// network namespace for which tasks can join. This only needs to be implemented
// if the driver MUST create the network namespace
type DriverNetworkManager interface {
	CreateNetwork(allocID string, request *NetworkCreateRequest) (*NetworkIsolationSpec, bool, error)
	DestroyNetwork(allocID string, spec *NetworkIsolationSpec) error
}

// DriverSignalTaskNotSupported can be embedded by drivers which don't support
// the SignalTask RPC. This satisfies the SignalTask func requirement for the
// DriverPlugin interface.
type DriverSignalTaskNotSupported struct{}

func (DriverSignalTaskNotSupported) SignalTask(taskID, signal string) error {
	return fmt.Errorf("SignalTask is not supported by this driver")
}

// DriverExecTaskNotSupported can be embedded by drivers which don't support
// the ExecTask RPC. This satisfies the ExecTask func requirement of the
// DriverPlugin interface.
type DriverExecTaskNotSupported struct{}

func (_ DriverExecTaskNotSupported) ExecTask(taskID string, cmd []string, timeout time.Duration) (*ExecTaskResult, error) {
	return nil, fmt.Errorf("ExecTask is not supported by this driver")
}

type HealthState string

var (
	HealthStateUndetected = HealthState("undetected")
	HealthStateUnhealthy  = HealthState("unhealthy")
	HealthStateHealthy    = HealthState("healthy")
)

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Use a driver that supports signaling (e.g. exec, docker)
2. Stop the task instead of signaling, or restart the allocation

When it happens

Trigger: Thrown at plugins/drivers/driver.go:123 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/f84c4a09256f18a2. Report an issue: GitHub.