grafana/k6 · error

require() can't be used with an empty specifier

Error message

require() can't be used with an empty specifier

What it means

ModuleSystem.Require() implements require() and refuses an empty specifier string before any resolution is attempted, because there is no module that an empty string could name. The check also runs after the usage-reporting step, so it fires on every require('') call regardless of the resolver state.

Source

Thrown at js/modules/require_impl.go:24

	"maps"
	"net/url"
	"strings"

	"github.com/grafana/sobek"

	"go.k6.io/k6/v2/internal/loader"
)

// Require is the actual call that implements require
func (ms *ModuleSystem) Require(specifier string) (*sobek.Object, error) {
	if !ms.resolver.locked {
		if err := ms.resolver.usage.Uint64("usage/require", 1); err != nil {
			ms.resolver.logger.WithError(err).Warn("couldn't report usage")
		}
	}

	if specifier == "" {
		return nil, errors.New("require() can't be used with an empty specifier")
	}

	rt := ms.vu.Runtime()
	parentModuleStr := getCurrentModuleScript(ms.vu)

	parentModule, _ := ms.resolver.sobekModuleResolver(nil, parentModuleStr)
	m, err := ms.resolver.sobekModuleResolver(parentModule, specifier)
	if err != nil {
		return nil, err
	}
	if wm, ok := m.(*goModule); ok {
		var gmi *goModuleInstance
		gmi, err = ms.getModuleInstanceFromGoModule(wm)
		if err != nil {
			return nil, err
		}
		exports := toESModuleExports(gmi.mi.Exports())
		return rt.ToValue(exports).ToObject(rt), nil

View on GitHub (pinned to 93accf6570)

Solutions

1. Pass a real module specifier: require('./helpers.js')
2. Guard dynamic specifiers: if (!specifier) throw new Error(`empty module specifier for feature ${feature}`)
3. Fix the data source (env var / config key) that produced the empty string

Example fix

// before
const mod = require(process.env.K6_MOD || '');

// after
const spec = process.env.K6_MOD;
if (!spec) throw new Error('K6_MOD must name a module');
const mod = require(spec);

function safeRequire(spec) {
  if (typeof spec !== 'string' || spec === '') {
    throw new Error(`invalid require specifier: ${JSON.stringify(spec)}`);
  }
  return require(spec);
}

const isSpecifier = (s) => typeof s === 'string' && s.trim().length > 0;

When it happens

Trigger: require('') literally, or require(variable) where variable is '' — commonly a module name built from env vars, config maps, or string concatenation that produced an empty string.

Common situations: Feature-flag-driven requires (require(FLAGS.feature ? './a' : '')); iterating a config list where one entry is missing; typos like require(`${prefix}`) with an empty prefix.

Related errors

• CommonJS's exports must not be null
• stack too big
• Error while parsing selector `${selector}` - selector cannot
• exported 'setup' must be a function
• exported 'teardown' must be a function

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/7e89c595467940da. Report an issue: GitHub.