A common requirement for Next.js projects is to require local files in Next.js pages (see markdown issue and i18next issue as examples).
In this case, you can configure your netlify.toml to make sure these files are included in the function runtime environment. This is necessary for pages that use fallback: true, SSR, preview mode, etc. For example:
[build]
command = "npm run build"
[functions]
# Includes all Markdown files inside the "files/" directory.
included_files = ["files/*.md"]Read more about functions configuration and included_files in our docs.