Server Action shape

next/server-actionserror / warningreactnextjs-16correctness

Why it matters

A "use server" module may only export async functions; inline actions cannot live in Client Components; action arguments are serialized so they cannot be functions; a <form action> in a Server Component must be a Server Action.

Fix

Make the export async (or move non-action exports elsewhere), move inline actions to a "use server" file, take serializable arguments, or add "use server" to the function body.

Credit

From the React team
A 'use server' module exposes async functions as Server Actions whose arguments and results must be serializable.
From the Next.js team
Specifies where Server Actions may be defined and how forms and mutations should call them.