I am not using any framework and I would like to add a custom 404 page. In Vercel’s documentation, they only provide information for users of frameworks.
>Solution :
See the documentation for Custom 404 Page – Static Site Generator (SSG)
Emit a
404.htmlfile to your Output Directory and it will be served as the 404 page when a route does not match any other static file.
TL;DR create a 404.html file and to the root of your site and Vercel will use that to serve requests that don’t match any resources.
A static site generator like Hugo creates plain old HTML pages that (typically) don’t operate as a Single-Page Application (SPA); there’s an HTML file for each page.
This is just like a regular, non-framework, non-SPA website which matches your application structure.