Unknown word error from CSS Minimizer plugin on React build

Question

The React build failed due to the CSS Minimizer plugin's "Unknown word" error. When I run npm run build, it continuously fails!

Failed to compile.

static/css/main.d3e3749c.css from Css Minimizer plugin static\css\main.d3e3749c.css:698:13: Unknown word [:1,0][static/css/main.d3e3749c.css:698,13]

My Node version is v16.14.0. Everything works well in npm start, but the build fails. Maybe this is due to PostCSS. I tried downgrading the version for the same, but it didn't work.

package.json

{
  "name": "frontend",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@emotion/react": "^11.8.1",
    "@emotion/styled": "^11.8.1",
    "@mui/icons-material": "^5.4.4",
    "@mui/material": "^5.4.4",
    "@testing-library/jest-dom": "^5.16.1",
    "@testing-library/react": "^12.1.2",
    "@testing-library/user-event": "^13.5.0",
    "axios": "^0.26.0",
    "emoji-mart": "^3.0.1",
    "moment": "^2.29.1",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-helmet-async": "^1.2.3",
    "react-infinite-scroll-component": "^6.1.0",
    "react-redux": "^7.2.6",
    "react-router-dom": "^6.2.1",
    "react-scripts": "5.0.0",
    "react-scroll-to-bottom": "^4.2.0",
    "react-slick": "^0.28.1",
    "react-toastify": "^8.2.0",
    "redux": "^4.1.2",
    "redux-devtools-extension": "^2.13.9",
    "redux-thunk": "^2.4.1",
    "slick-carousel": "^1.8.1",
    "socket.io-client": "^4.4.1",
    "web-vitals": "^2.1.3",
    "webfontloader": "^1.6.28"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "autoprefixer": "^10.4.2",
    "postcss": "^8.4.8",
    "tailwindcss": "^3.0.23"
  }
}

Answer 1

I had the same problem and, in my case, the error was caused by tailwind JIT mode. I had a style like:

top-[${positionFromTop}]

in one of my files, which caused the error.

To find the cause of your error, you should run the npx tailwindcss -i ./src/{YOUR_MAIN_CSS_FILE}.css -o ./dist/output.css --watch command with the tailwind CLI, and then check the output.css for any syntax errors. Then just fix the style that causes the syntax error.