Unstyled UI shows up on the first load. CSS is not loading properly on production build

[mplakhtiy]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Current behavior 😯

Unstyled UI shows up on the first load when using material ui examples nextjs-with-typescript or nextjs stackblitz

This also happens within my own project with the latest packages versions.

Expected behavior 🤔

Ui is loaded with styles on the first load.

Steps to reproduce 🕹

Steps:

1. Go to https://stackblitz.com/github/mui/material-ui/tree/master/examples/nextjs or https://stackblitz.com/github/mui/material-ui/tree/master/examples/nextjs-with-typescript
2. Reload the ui within stackblitz (it can be seen that mui light bulb icon is large for a fraction of a second)

Context 🔦

No response

Your environment 🌎

`npx @mui/envinfo`

  Don't forget to mention which browser you used.
  Output from `npx @mui/envinfo` goes here.

[PupoSDC]

Can confirm this is indeed not working 😢
Best way to see this is to disable JS and see that the rendered page is unstyled.

[PupoSDC]

I tried to go a bit deeper on this and the only thing I found out is that initialProps.html seems to be empty.

  const initialProps = await Document.getInitialProps(ctx);
  const emotionStyles = extractCriticalToChunks(initialProps.html);

This is caused by React 18. With React 17 initialProps.html is properly defined.

I will open a ticket with next js.

[PupoSDC]

Turns out opening an issue won't be needed. This is indeed an issue with next.

It's fixed on Next version 12.1.7-canary.6.

[balazsorban44]

This can be closed. See vercel/next.js#36915 (comment)

Related PR: vercel/next.js#36792

And related issue already reporting this: vercel/next.js#36675 (comment)

[mplakhtiy]

@PupoSDC @balazsorban44 Thanks a lot for the quick response! Can confirm it works with the next@12.1.7-canary.6.

[siriwatknp]

Duplicate of #30410

[vascojm82]

Turns out opening an issue won't be needed. This is indeed an issue with next.

It's fixed on Next version 12.1.7-canary.6.

I upgraded from v12.0.10 to v12.1.7-canary.39 and I still have this issue happening, anybody can help?