Hi. While making a repo to reproduce this error, I think I found what was generating it.

In our _app.jsx file we were importing two files of fontawesome-free.

import '@fortawesome/fontawesome-free/css/all.min.css';
import '@fortawesome/fontawesome-free/js/all';

(This comes from a workaround for the previous version of mdb-react-ui-kit that didn't work with Pages Router).

When these two files are imported the error happens, removing the second one seems to solve the issue.

I should have checked this before. Thanks for your help.

Hi, could you tell me more about reproducing this error? I'm using next v14.1.3, mdb-react-ui-kit v7.2.0. New Next.js config with app router, without src folder and it works perfectly. The only thing I needed to add is "use client" directive. It shouldn't be neccesary in component like this, but at the moment it is - fix is on the way

// page.tsx
"use client";
import { useState } from "react";
import { MDBIcon } from "mdb-react-ui-kit";

export default function Home() {
  const [show, setShow] = useState(true);
  return (
    <>
      <button onClick={() => setShow(!show)}>{show ? "Hide" : "Show"}</button>
      {show && <MDBIcon icon="camera-retro" />}
    </>
  );
}

Also try to mark the problematic component as client component and let me know if the problem persists.