useEffect Error: Minified React error #321 (GTM implementation instead of google analitycs)

Question

Why I got Minified React Error #321 during the next build compilation? Did I mess up with useEffect() ?

Part of the error throwed :

Automatically optimizing pages .(node:763) ExperimentalWarning: The fs.promises API is experimental
(node:762) ExperimentalWarning: The fs.promises API is experimental
(node:761) ExperimentalWarning: The fs.promises API is experimental
Automatically optimizing pages .Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:10945:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:10950:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:7133:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:1023:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:1026:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:1031:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:1031:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:1041:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/index.js:899:16)

Error occurred prerendering page "/". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Automatically optimizing pages ..Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21744:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21749:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:14938:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:899:16)
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21744:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21749:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:14938:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:899:16)

Error occurred prerendering page "/XXX/XXX/syndic-copropriete". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

Error occurred prerendering page "/XXX/XXX/aides-renovation-energetique". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Automatically optimizing pages ..Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21744:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:21749:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:14938:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/[formationUrl]/[courseCode].js:899:16)

Error occurred prerendering page "/XXX". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21165:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21170:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:14443:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:899:16)

Error occurred prerendering page "/XXX/inscription". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Automatically optimizing pages .Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21165:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21170:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:14443:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:899:16)
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21165:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:21170:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:14443:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/inscription.js:899:16)

Error occurred prerendering page "/XXX/inscription". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20913:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20918:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:14649:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:899:16)

Error occurred prerendering page "/XXX/merci". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

Error occurred prerendering page "/XXX/inscription". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:6809:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:6814:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:4227:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:907:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:910:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:915:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:915:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:925:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:461:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/_error.js:783:16)

Error occurred prerendering page "/404". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Automatically optimizing pages ..Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20913:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20918:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:14649:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:899:16)

Error occurred prerendering page "/XXX/merci". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
Automatically optimizing pages ...Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.
    at Z (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20913:404)
    at module.exports.viRO.exports.useEffect (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:20918:356)
    at App (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:14649:29)
    at d (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1114:498)
    at $a (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1117:16)
    at a.b.render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:476)
    at a.b.read (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1122:18)
    at renderToString (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:1132:364)
    at render (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:577:16)
    at Object.renderPage (/XXX/XXX/XXX/XXX/.next/serverless/pages/[domainCode]/merci.js:899:16)

Error occurred prerendering page "/XXX/merci". Read more: https://err.sh/next.js/prerender-error
Error: Minified React error #321; visit https://reactjs.org/docs/error-decoder.html?invariant=321 for the full message or use the non-minified dev environment for full errors and additional helpful warnings.

> Build error occurred
Error: Export encountered errors
    at _default (/usr/local/lib/node_modules/next/dist/export/index.js:19:1164)
    at process._tickCallback (internal/process/next_tick.js:68:7)
Automatically optimizing pages .%                                                                                                       

What I tried:

Implemented the gtag on my next Js app. I followed the Zeit example from

https://github.com/zeit/next.js/tree/canary/examples/with-google-analytics

I precise something important this example show us how to add google analytics and not GTM that's two very differentes thing, but you just need to change:

// pages/_document.tsx

import Document, { Head, Main, NextScript } from 'next/document';
import { Fragment } from 'react';

export default class MyDocument extends Document {
    setGoogleTags() {
        return {
            __html: `
            (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-XXXXX');
          `
        };
    }

    render() {
        return (
            <html>
                <Head>
                    <Fragment>
                        <script dangerouslySetInnerHTML={this.setGoogleTags()} />
                    </Fragment>
                </Head>
                <body>
                    {/* <Fragment> */}
                        {/* <!-- Google Tag Manager (noscript) --> */}
                        <noscript>
                            <iframe
                                src="https://www.googletagmanager.com/ns.html?id=GTM-XXXXXX"
                                height="0"
                                width="0"
                                style={{ display: 'none', visibility: 'hidden' }}
                            ></iframe>
                        </noscript>
                    <Main />
                    <NextScript />
                </body>
            </html>
        );
    }
}

I've just changed one thing is _app.js to _app.tsx :

//_app.tsx

import Router from 'next/router';

import React, { useEffect, ReactElement } from 'react';

import { AppProps } from 'next/app';
import '../CSS/index.css';
import * as gtag from '../lib/gtag';
import '@brainhubeu/react-carousel/lib/style.css';

export default function  App({ Component, pageProps }: AppProps): ReactElement {
    useEffect(() => {
        const handleRouteChange = (url: string) => {
            gtag.pageview(url);
        };
        Router.events.on('routeChangeComplete', handleRouteChange);
        return () => {
            Router.events.off('routeChangeComplete', handleRouteChange);
        };
    }, []);

    return <Component {...pageProps} />;
}

https://github.com/zeit/next.js/issues/160#issuecomment-634502987

Answer 1

It might because you are importing React twice on the page:

import { useEffect } from 'react';
import Router from 'next/router';

import React, { ReactElement } from 'react';

should just be:

import React, { useEffect, ReactElement } from 'react';
import Router from 'next/router';

Edit

Try to delete your node_modules and .next folder from your local project and then run your npm run build again. That seemed to solve it for me.