Next.js · next build (prerender)

Only plain objects can be passed to Client Components

Error: Only plain objects, and a few built-ins, can be passed to Client Components from Server Components. Classes or null prototypes are not supported.
  {v: {c: 5}}
      ^^^^^^

What it means

Props going from a Server Component to a Client Component are serialized. Class instances can't be: Prisma Decimal values, SDK objects (a Stripe or OpenAI response object), Mongoose documents, or your own classes.

Common causes

• Passing a Prisma row with a Decimal column straight to a client table
• Passing a whole SDK response object instead of the fields you need
• Objects created with Object.create(null)

How to fix it

1. Map to plain fields before passing: { id, name, price: Number(row.price) }
2. Convert Decimal with .toNumber() or .toString()
3. Only pass what the client actually renders

const rows = await db.product.findMany();
- return <Table rows={rows} />
+ return <Table rows={rows.map((r) => ({ id: r.id, name: r.name, price: r.price.toNumber() }))} />

Prompt for Cursor or Claude Code

Next.js says only plain objects can be passed to Client Components. Find the prop that carries a class instance (Prisma Decimal, an SDK object or a custom class) and map it to plain serializable fields on the server before passing it down.

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