What causes "must specify plugin type to deregister" in hashicorp/nomad?

Pass the correct plugin type constant (e.g. dynamicplugins.PluginTypeCSIDriver) as the first argument

must specify plugin type to deregister

Error message

must specify plugin type to deregister

What it means

DeregisterPlugin requires both a plugin type and name to locate the registration to remove. The type parameter identifies which plugin map (e.g. csi-driver, csi-node) to search. An empty type means the lookup cannot proceed, so the registry returns this developer-aid error.

Source

Thrown at client/dynamicplugins/registry.go:247

	defer d.broadcastersLock.Unlock()

	broadcaster, ok := d.broadcasters[ptype]
	if !ok {
		broadcaster = newPluginEventBroadcaster()
		d.broadcasters[ptype] = broadcaster
	}

	return broadcaster
}

func (d *dynamicRegistry) DeregisterPlugin(ptype, name, allocID string) error {
	d.pluginsLock.Lock()
	defer d.pluginsLock.Unlock()

	if ptype == "" {
		// This error shouldn't make it to a production cluster and is to aid
		// developers during the development of new plugin types.
		return errors.New("must specify plugin type to deregister")
	}
	if name == "" {
		// This error shouldn't make it to a production cluster and is to aid
		// developers during the development of new plugin types.
		return errors.New("must specify plugin name to deregister")
	}
	if allocID == "" {
		return errors.New("must specify plugin allocation ID to deregister")
	}

	pmap, ok := d.plugins[ptype]
	if !ok {
		// If this occurs there's a bug in the registration handler.
		return fmt.Errorf("no plugins registered for type: %s", ptype)
	}

	infos, ok := pmap[name]
	if !ok {

View on GitHub (pinned to 482b49bf1a)

Solutions

Pass the correct plugin type constant (e.g. dynamicplugins.PluginTypeCSIDriver) as the first argument
Trace where ptype originates and validate it is non-empty before the call
Log the caller arguments to identify which code path produces the empty type

Example fix

// before
err := registry.DeregisterPlugin("", pluginName, allocID)
// after
if ptype == "" {
    return fmt.Errorf("cannot deregister plugin %q: plugin type is empty", pluginName)
}
err := registry.DeregisterPlugin(ptype, pluginName, allocID)

Defensive patterns

Strategy: validation

Validate before calling

if ptype == "" {
    return fmt.Errorf("deregister: plugin type is required")
}
err := registry.DeregisterPlugin(ptype, name, allocID)

Type guard

func canDeregister(ptype, name, allocID string) bool {
    return ptype != "" && name != "" && allocID != ""
}

Try / catch

err := registry.DeregisterPlugin(ptype, name, allocID)
if err != nil {
    if strings.Contains(err.Error(), "must specify plugin type") {
        return fmt.Errorf("plugin type %q invalid: %w", ptype, err)
    }
    return err
}

Prevention

Use the exported dynamicplugins.PluginType* constants instead of raw strings
Log the caller context when ptype comes from a dynamic field
Validate deregistration inputs where the alloc lifecycle builds them

When it happens

Trigger: Calling Registry.DeregisterPlugin(ptype, name, allocID) with ptype == "", usually when the caller's stored plugin type variable was never set or was lost during a type/attribute lookup.

Common situations: A plugin deregistration handler derives the type from a request field that is empty (e.g. job/ CSI plugin info missing), or refactored code passes the wrong variable position.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/5522ed71a88761c6. Report an issue: GitHub.