All inertia requests must receive a valid inertia response, however a plain json response was received.

Answer:

When working with Inertia.js, all requests should receive a valid Inertia response. However, in your case, a plain JSON response was received instead. This means that the response you are getting does not adhere to the Inertia.js response format.

An Inertia.js response consists of a few key attributes:

• component: The name of the Vue or React component that should be rendered on the client side.
• props: An object containing data that should be passed to the component.
• url: The URL that should be updated in the browser’s address bar.
• version: A version number that can be used for cache invalidation.

To provide a valid Inertia response, you should structure your server-side code to return a response that includes these attributes. Here’s an example of how you can structure your server-side code to provide a valid Inertia response using PHP and Laravel:

<?php

  use Inertia\Inertia;

  // ...

  public function index()
  {
      // Your logic to fetch the necessary data and perform any computations

      // Return an Inertia response
      return Inertia::render('HomePage', [
          'data' => $data,
          // other data that should be passed to the component
      ]);
  }
  

In this example, the Inertia::render() method is used to create a valid Inertia response. The first argument is the name of the Vue or React component you want to render, and the second argument is an array of data that should be passed to the component as props.

Make sure to adjust the code example according to the programming language and framework you are using. The key is to return a response that adheres to the Inertia.js response format.