You're integrating Tailwind with a tool that relies on an older version of PostCSS. You can use this doc https://tailwindcss.com/docs/installation#post-css-7-compatibility-build

worked for me :

npm install tailwindcss@npm:@tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

Uninstall Tailwind and re-install using the compatibility build instead

npm uninstall tailwindcss postcss autoprefixer
npm install tailwindcss@npm:@tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

I got the same issue using laravel 8, So Try uninstalling tailwind using "npm uninstall tailwindcss" and install it back using

npm install tailwindcss@compat

then run "npx tailwindcss init" if you don't have the tailwing.config.js file

after then run npm run watch.

still follow up the laravel documentation for more when you get stuck https://laravel.com/docs/8.x/mix#tailwindcss

The above solution fixed TaildWindCss PostCss issue, but I faced another error, which is :

TypeError: getProcessedPlugins is not a function

The Solution for is to upgrade Node version, in my case I upgraded from v10 to v15 which fixed my issue.

Oddly I had this issue on one dev machine . . . but not the other, with identical package.json file, and using identical node/npm (15.5/7.3). I deleted node_modules, reinstalled. Did not fix it.

Final fix, which is bizarre, is after the node module reinstall, all I did was:

npm uninstall tailwindcss

then

npm i tailwindcss --save-dev

(note, not using the compatibility package) and it worked fine. I do have to use --legacy-peer-deps when re-installing the node_modules, so somehow the order of installation mattered in my scenario . . .

Had the same issue and did the following to resolve;

1. Check your npm version using npm -ver, and make sure to install the latest version
2. Also check your Node version and update to the latest version through this URL: "https://nodejs.org/en/download/"

This solution below should work perfectly.

Run the following commands

npm uninstall tailwindcss postcss autoprefixer

npm install tailwindcss@npm:@tailwindcss/postcss7-compat @tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

EDIT: Removed some erranous spaces.

you have to uninstall all these

npm uninstall autoprefixer postcss tailwindcss

Then run this command, it's will generate tailwind.css file automatically

vue add tailwind 

I tried everything and was still having TypeError: getProcessedPlugins is not a function error. What fixed the issue for me was upgrading the nodejs version.

To check the installed node version

node -v

my node version was v10.23.0 and was using Ubuntu. I upgraded to v14.15.4.

Here is how I upgraded node

sudo apt update
curl -sL https://deb.nodesource.com/setup_14.x | sudo bash -
sudo apt-get install -y nodejs
node -v

also I cleaned the cache to be more sure

npm cache clean -f

After upgrading I deleted node_modules folder inside project. ran npm install and then ran npm run dev inside the project folder.

This is the only solution that worked for me, so sharing it.

I was getting dependency tree error when I try uninstall and install with compact version. So I had to install with yarn instead and it works.

npm uninstall tailwindcss postcss autoprefixer
yarn add tailwindcss@npm:@tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

npm uninstall tailwindcss postcss autoprefixer

then

vue add tailwind 

to use the vue cli plugin https://www.npmjs.com/package/vue-cli-plugin-tailwind

I'm on a Mac using VueJS 3 (@vue/cli 4.5.11). For me the following two commands solved the issue:

npm uninstall tailwindcss postcss autoprefixer
npm install -D tailwindcss@latest postcss@latest autoprefixer@latest

This installed:

• tailwindcss 2.1.1
• postcss 8.2.10
• autoprefixer 10.2.5

To resolve this error, uninstall Tailwind and re-install using the compatibility build instead:

npm uninstall tailwindcss postcss autoprefixer

npm install -D tailwindcss@npm:@tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9

Solution from Tailwind documentation v2

The accepted answer is now out of date.

As of v2.0, Tailwind CSS depends on PostCSS 8. The previously accepted answer states how to downgrade to PostCSS 8

Instead please do the following to get everything running on all the latest versions

yarn add @storybook/addon-postcss

Then edit your .storybook/main.js

module.exports = {
  stories: [
    "../stories/**/*.stories.mdx",
    "../stories/**/*.stories.@(js|jsx|ts|tsx)",
  ],
  addons: [
    "@storybook/addon-links",
    "@storybook/addon-essentials",
    {
      name: "@storybook/addon-postcss",
      options: {
        postcssLoaderOptions: {
          implementation: require("postcss"),
        },
      },
    },
  ],
};

https://storybook.js.org/addons/@storybook/addon-postcss

@dlporter98

While not using Vue, I hope this helps others with a similar issue. In my case, I was using TailwindCSS with Gulp (^4.0.2) and was able to solve the error by removing tailwind and its dependencies:

npm uninstall tailwindcss gulp-postcss autoprefixer

Then installed them again but explicitly specified the postcss plugin as version 9:

npm install tailwindcss autoprefixer gulp-postcss@9

I tried with gulp-postcss@latest, but found it kept installing version 8.3.1 and didn't resolve the error. More information can be seen here: https://github.com/postcss/postcss/wiki/PostCSS-8-for-end-users

Otherwise, I would echo the use of the Tailwind compatibility version.

For those upgrading to Tailwind 3, and experiencing this issue, the following instructions from Tailwind's own troubleshooting are what fixed it for me.

Specifically, changing your start and build scripts:

"start": "concurrently \"npm run start:css\" \"react-scripts start\"",
"start:css": "tailwindcss -o src/tailwind.css --watch",
"build": "tsc && npm run build:css && react-scripts build",
"build:css": "NODE_ENV=production tailwindcss -o src/tailwind.css -m",

You'll have to install concurrently and npm-run-all, though.

The following is my postcss.config.js:

module.exports = {
  plugins: {
    tailwindcss: {},
    autoprefixer: {},
  },
}

This will mean that you'll have to import tailwind.css instead of index.css in your index file index.{tsx,js} for the project.

And if this worked for you, keep in mind you might no longer need @craco/craco installed.

I also faced this issue while upgrading. previously I done the setup using postCSS.

official documentation says

Note that Tailwind CSS v3.0 requires PostCSS 8, and no longer supports PostCSS 7. If you can’t upgrade to PostCSS 8, we recommend using Tailwind CLI instead of installing Tailwind as a PostCSS plugin.

So this time i done the setup using cli. https://tailwindcss.com/docs/installation

1. yarn remove tailwindcss postcss autoprefixer
yarn add --dev tailwindcss@latest @tailwindcss/typography@latest @tailwindcss/forms@latest @tailwindcss/aspect-ratio@latest @tailwindcss/line-clamp@latest postcss@latest autoprefixer@latest

2. npx tailwindcss -i ./src/assets/css/style.css -o ./src/assets/css/tailwind.css --watch

And in package.json need to do this change

https://tailwindcss.com/docs/content-configuration#it-just-isn-t-working-properly

my package.json

"start": "concurrently \"npm run start:css\" \"react-scripts start\"",
"start:css": "tailwindcss -o src/assets/css/tailwind.css --watch",
"build": "tsc && npm run build:css && react-scripts build",
"build:css": "NODE_ENV=production tailwindcss -o src/assets/css/tailwind.css -m",

This answer helped me to resolve the issue https://stackoverflow.com/a/70492649/7225816

With Vue 3 and Tailwindcss 3

1. Create tailwind.config.js
2. Create postcss.config.js
3. Add following in postcss.config.js

module.exports = {
  plugins: {
    tailwindcss: {
      config: './tailwind.config.js'
    }
  }
}

The above configuration works fine with latest postcss, autoprefixer, vue 3 and tailwind 3

This worked for me: running "npm install tailwindcss postcss" and "npm install tailwindcss autoprefixer"

this seperates installation of postcss and autoprefixer independently.

Yarn equivalent for those who are stuck with PostCSS v8 due to using a framework like Vuepress v1:

yarn add -D tailwindcss@npm:@tailwindcss/postcss7-compat postcss@^7 autoprefixer@^9