export const metadata = { title: Error: make sure your module has a default export of a service., }

{metadata.title}

If you get the following error while building your Medusa application:

bash

...doesn't seem to have a main service exported -- make sure your module has a default export of a service

Why this Error Occurred

This error occurs when you set the resolve path of a module provider to point directly to a service file instead of the module directory.

For example, if you set the resolve path to ./src/modules/slack/service:

module.exports = defineConfig({
  // ...
  modules: [
    {
      resolve: "@medusajs/medusa/notification",
      options: {
        providers: [
          {
            resolve: "./src/modules/slack/service",
            id: "slack",
            options: {
              channels: ["slack"],
              webhook_url: process.env.SLACK_WEBHOOK_URL,
              admin_url: process.env.SLACK_ADMIN_URL,
            },
          },
        ],
      },
    },
  ],
})

You'll get the error because the resolve path is pointing to the service file of the module provider, while it should point to the module directory.

How to Fix it

To fix the error, set the resolve path to point to the module directory instead of the service file. For example:

module.exports = defineConfig({
  // ...
  modules: [
    {
      resolve: "@medusajs/medusa/notification",
      options: {
        providers: [
          {
            resolve: "./src/modules/slack",
            id: "slack",
            options: {
              channels: ["slack"],
              webhook_url: process.env.SLACK_WEBHOOK_URL,
              admin_url: process.env.SLACK_ADMIN_URL,
            },
          },
        ],
      },
    },
  ],
})