[core] Missing @mui/system dependency with MUI v6

[caelus-dev]

Steps to reproduce

Hello!

I tried to upgrade from MUI v5 to v6. So as the official document stated, I just changed the @mui/material to the newest version and left everything else unchanged.

    "@emotion/react": "*",
    "@emotion/styled": "*",
    "@fontsource/roboto": "*",
    "@mui/icons-material": "*",
    "@mui/material": "^6.1.4",
    "@mui/x-date-pickers": "^7.21.0",
    "react": "^18.2.0",

However after changing the MUI v5 to v6, I got the following error: @mui/system is missing.

[ERROR] Could not resolve "@mui/system/RtlProvider"
[ERROR] Could not resolve "@mui/system"

As @flaviendelangle suggested in another conversation, I checked if the @mui/system is installed with yarn info, and turned out @mui/system is totally missing. The yarn build also confirms the problem:

foo@workspace:. doesn't provide @mui/system (paa105), requested by @mui/x-date-pickers.

I tried yarn explain peer-requirements command, but it says:
command doesn't support this warning type yet

I also tried to clean the yarn cache, delete folders, use other pc but nothing solved the problem.

Current behavior

@mui/system is not installed by "@mui/material": "^6.1.4"

Expected behavior

@mui/system should be installed by "@mui/material": "^6.1.4"

Context

No response

Your environment

No response

Search keywords: dependency @mui/system

[LukasTy]

Hello @caelus-dev, are you using yarn >1 with the PnP module resolution mechanism?

This case is listed in their FAQ.

Creating a .yarnrc.yml file with the following contents fixes this issue.

packageExtensions:
  "@mui/x-date-pickers@*":
    dependencies:
      "@mui/system": "*"

We could list our packages in their known list to avoid this manual labor.
https://github.com/yarnpkg/berry/blob/master/packages/yarnpkg-extensions/sources/index.ts
WDYT @mui/code-infra?

P.S. This applies to all the packages having the @mui/system peer dependency:
https://github.com/search?q=repo%3Amui%2Fmui-x+%22%40mui%2Fsystem%22%3A&type=code

[caelus-dev]

Hi @LukasTy , thank you for your answer!

are you using yarn >1 with the PnP module resolution mechanism?

Yes, I use yarn 4.1.0 with pnp module, but I also tried the most recent yarn 4.5.1.

Creating a .yarnrc.yml file with the following contents fixes this issue.

The yarn build no longer shows the error, but seems like the @mui/system package is still missing after setting the packageExtensions. Only workaround I found to put @mui/system directly in the packages.json as dependency.