medusajs/medusa · warning

The subscriber in ${path} is not a function. skipped.

Error message

The subscriber in ${path} is not a function. skipped.

What it means

During startup, the SubscriberLoader validates every file in src/subscribers. validateSubscriber requires the default export to be a function (the event handler). If subscriber.default is missing or not a function, the file is skipped with this warning and its handler will never receive events.

Source

Thrown at packages/core/framework/src/subscribers/subscriberLoader.ts:85

    const handler = subscriber.default

    if (!handler || typeof handler !== "function") {
      /**
       * If the handler is not a function, we can't use it
       */
      this.logger.warn(`The subscriber in ${path} is not a function. skipped.`)
      return false
    }

View on GitHub (pinned to 5e06e544a2)

Solutions

1. Add a default-exported async handler to the file: export default async function productCreatedHandler({ event, container }) { ... }
2. If the file is not meant to be a subscriber, move it out of src/subscribers (e.g. to src/lib) so the loader ignores it
3. Prefix the file with _ or set config.isFileSkipped if you intentionally want the loader to skip it

Example fix

// before
export const config = { event: "product.created" }
export function handleProductCreated(args) { /* ... */ }

// after
export const config = { event: "product.created" }
export default async function handleProductCreated({ event, container }) {
  /* ... */
}

type SubscriberModule = { default: (args: any) => Promise<void>; config: { event: string | string[] } }
const isValidSubscriber = (m: any): m is SubscriberModule =>
  typeof m?.default === "function" && !!m?.config?.event

When it happens

Trigger: A file in src/subscribers (or a plugin's subscribers dir) that exports no default function, exports a class/object/constant as default, or only exports named members (e.g. only `config`).

Common situations: Forgetting `export default async ({ event, container }) => {...}` and only exporting the config object; renaming the handler to a named export; scaffold files from tutorials that omit the default export.

Related errors

• The subscriber in ${path} is missing a config. skipped.
• The subscriber in ${path} is missing an event in the config.
• The subscriber in ${path} has an invalid event config. The e
• Invalid default export found in ${absolutePath}. Make sure t
• Failed to clear events for eventGroupId - ${flowEventGroupId

AI-assisted analysis of medusajs/medusa@5e06e544a2 (2026-08-27). Data as JSON: /api/errors/3dfeee2002e315b2. Report an issue: GitHub.