Routing static assets
When you use a JavaScript framework like Next.js on Cloudflare Pages, the framework adapter (ex: @cloudflare/next-on-pages) automatically generates a _routes.json file, which defines specific paths of your app's static assets. This file tells Cloudflare, for these paths, don't run the Worker, you can just serve the static asset on this path (an image, a chunk of client-side JavaScript, etc.)
The framework adapter handles this for you — you typically shouldn't need to create your own _routes.json file.
If you need to, you can define your own _routes.json file in the root directory of your project. For example, you might want to declare the /favicon.ico path as a static asset where the Worker should not be invoked.
You would add it to the excludes filed of your _routes.json file:
{ "version": 1, "exclude": ["/favicon.ico"]}During the build process, @cloudflare/next-on-pages will automatically generate its own _routes.json file in the output directory. Any entries that are provided in your own _routes.json file (in the project's root directory) will be merged with the generated file.