# Missing middleware

Learn how to configure the Croct middleware.

If you forget to configure the [middleware](/reference/sdk/nextjs/api/functions/proxy) in your Next.js application, you will see an error like the one below:

> **Error**
>
> Did you forget to configure Croct's middleware?

This happens because all SDK functions depend on request-specific information provided by the middleware to work properly.

Check the [configuration section](/reference/sdk/nextjs/manual-installation#middleware) for instructions on how to set up the middleware.