Response body object should not be disturbed or locked

[MikeyZhang75]

When using clerkPlugin and expecting data from the body, you encounter: "Response body object should not be disturbed or locked"

What I've Tried:

• Removing the Body Schema:

{
  body: t.Object({
    name: t.String(),
  }),
}

• Removing the auth Parameter(resolves the issue):

async ({ body }) => { ... }

Tested on Elysia versions 1.2.25 and 1.2.24.

Full API Code:

// app/api/[[...slugs]]/route.ts
import { Elysia, error, t } from "elysia";
import { swagger } from "@elysiajs/swagger";
import { clerkPlugin } from "elysia-clerk";

const app = new Elysia({ prefix: "/api" })
	.use(swagger())
	.use(clerkPlugin())
	.post(
		"/user",
		async ({ auth, body }) => {
			if (!auth?.userId) {
				return error(401);
			}

			return body;
		},
		{
			body: t.Object({
				name: t.String(),
			}),
		},
	);

export const GET = app.handle;
export const POST = app.handle;

Package.json:

{
  "name": "clerk-elysia-test",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "dev": "next dev --turbopack",
    "build": "next build",
    "start": "next start",
    "lint": "next lint"
  },
  "dependencies": {
    "@clerk/nextjs": "^6.12.8",
    "@elysiajs/swagger": "^1.2.2",
    "elysia": "^1.2.25",
    "elysia-clerk": "^0.9.7",
    "next": "15.2.3",
    "react": "^19.0.0",
    "react-dom": "^19.0.0"
  },
  "devDependencies": {
    "@eslint/eslintrc": "^3",
    "@tailwindcss/postcss": "^4",
    "@types/bun": "^1.2.5",
    "@types/node": "^20",
    "@types/react": "^19",
    "@types/react-dom": "^19",
    "eslint": "^9",
    "eslint-config-next": "15.2.3",
    "tailwindcss": "^4",
    "typescript": "^5"
  }
}

[MikeyZhang75]

Not sure whether you need .env or not, but i will provide anyway

NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY= "pk_test_SOMETHING"
CLERK_PUBLISHABLE_KEY= "pk_test_SOMETHING"
CLERK_SECRET_KEY= "sk_test_SOMETHING"

NEXT_PUBLIC_CLERK_SIGN_IN_URL=/sign-in
NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL=/
NEXT_PUBLIC_CLERK_SIGN_UP_FALLBACK_REDIRECT_URL=/

NEXT_PUBLIC_CLERK_SIGN_UP_URL=/sign-up
NEXT_PUBLIC_CLERK_SIGN_UP_FALLBACK_REDIRECT_URL=/
NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL=/

[MikeyZhang75]

Diagnosis Summary

✅ Working Method: auth from @clerk/nextjs/server

import { auth } from "@clerk/nextjs/server";

const { userId } = await auth();

• Using this method, the Response body object should not be disturbed or locked issue is resolved.

❌ Issue: createClerkClient from @clerk/backend

Not confirmed if this is being used in your clerkPlugin, but here's the example that may not work as expected:

import { createClerkClient } from "@clerk/backend";

const requestState = await clerkClient.authenticateRequest(request);
const auth = requestState.toAuth();

if (!requestState.isSignedIn || !auth || !auth.userId) {
  return error(401, {
    retCode: 1,
    retMsg: "Unauthorized",
  });
}

• Without using the clerkPlugin, and instead using the official method, the Response body object should not be disturbed or locked issue still occurs.

❓ Question

• Is there any workaround?
• I'm using Next.js 15, not a pure standalone Elysia API.