Rails 8.1 with ActiveAdmin 4-beta19 #8888

setoelkahfi · 2025-12-14T11:57:02Z

setoelkahfi
Dec 14, 2025

I'm trying to setup ActiveAdmin 4-beta19 for my Rails 8.1 application to no avail. I've been following this discussion but there's no mention of cssbundling-rails like someone mentioned here. I keep getting error that my tailwindcss file is not found:

My Gemfile:

source "https://rubygems.org"

gem "devise"

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
gem "rails", "~> 8.1"
# The modern asset pipeline for Rails [https://github.com/rails/propshaft]
gem "propshaft"
# Use postgresql as the database for Active Record
gem "pg", "~> 1.1"
# Use the Puma web server [https://github.com/puma/puma]
gem "puma", ">= 5.0"
# Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
gem "importmap-rails"
# Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
gem "turbo-rails"
# Hotwire's modest JavaScript framework [https://stimulus.hotwired.dev]
gem "stimulus-rails"
# Use Tailwind CSS [https://github.com/rails/tailwindcss-rails]
gem "tailwindcss-rails", "~> 3.3.1"
# Build JSON APIs with ease [https://github.com/rails/jbuilder]
gem "jbuilder"

# Use Active Model has_secure_password [https://guides.rubyonrails.org/active_model_basics.html#securepassword]
# gem "bcrypt", "~> 3.1.7"

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem "tzinfo-data", platforms: %i[ windows jruby ]

# Use the database-backed adapters for Rails.cache, Active Job, and Action Cable
gem "solid_cache"
gem "solid_queue"
gem "solid_cable"

# Reduces boot times through caching; required in config/boot.rb
gem "bootsnap", require: false

# Deploy this application anywhere as a Docker container [https://kamal-deploy.org]
gem "kamal", require: false

# Add HTTP asset caching/compression and X-Sendfile acceleration to Puma [https://github.com/basecamp/thruster/]
gem "thruster", require: false

# Use Active Storage variants [https://guides.rubyonrails.org/active_storage_overview.html#transforming-images]
# gem "image_processing", "~> 1.2"

gem "activeadmin", "4.0.0.beta19"

group :development, :test do
  # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
  gem "debug", platforms: %i[ mri windows ], require: "debug/prelude"

  # Static analysis for security vulnerabilities [https://brakemanscanner.org/]
  gem "brakeman", require: false

  # Omakase Ruby styling [https://github.com/rails/rubocop-rails-omakase/]
  gem "rubocop-rails-omakase", require: false
end

group :development do
  # Use console on exceptions pages [https://github.com/rails/web-console]
  gem "web-console"
  gem "letter_opener"
end

group :test do
  # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
  gem "capybara"
  gem "selenium-webdriver"
end

gem "cssbundling-rails", "= 1.4.1"

My package.json:

{
  "name": "app",
  "private": "true",
  "scripts": {
    "build:css": "tailwindcss -i ./app/assets/stylesheets/application.tailwind.css -o ./app/assets/builds/application.css --minify -c tailwind.config.js && tailwindcss -i ./app/assets/stylesheets/active_admin.css -o ./app/assets/builds/active_admin.css --minify -c tailwind-active_admin.config.js"
  },
  "dependencies": {
    "@activeadmin/activeadmin": "4.0.0-beta19"
  },
  "devDependencies": {
    "tailwindcss": "^3.3.1"
  }
}

I have another Rails 8.1 app runs well with package.json:

{
  "name": "app",
  "private": "true",
  "scripts": {
    "build:css": "tailwindcss -i ./app/assets/stylesheets/application.tailwind.css -o ./app/assets/builds/application.css --minify -c tailwind.config.js && tailwindcss -i ./app/assets/stylesheets/active_admin.css -o ./app/assets/builds/active_admin.css --minify -c tailwind-active_admin.config.js"
  },
  "dependencies": {
    "@activeadmin/activeadmin": "4.0.0-beta15"
  },
  "devDependencies": {
    "tailwindcss": "^3.4.17"
  }
}

Gemfile:

source "https://rubygems.org"

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
gem "rails", "~> 8.1"
# The modern asset pipeline for Rails [https://github.com/rails/propshaft]
gem "propshaft"
# Use sqlite3 as the database for Active Record
gem "sqlite3", ">= 2.1"
# Use the Puma web server [https://github.com/puma/puma]
gem "puma", ">= 5.0"
# Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
gem "importmap-rails"
# Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
gem "turbo-rails"
# Hotwire's modest JavaScript framework [https://stimulus.hotwired.dev]
gem "stimulus-rails"
# Build JSON APIs with ease [https://github.com/rails/jbuilder]
gem "jbuilder"

# Use Active Model has_secure_password [https://guides.rubyonrails.org/active_model_basics.html#securepassword]
# gem "bcrypt", "~> 3.1.7"

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem "tzinfo-data", platforms: %i[windows jruby]

# TinyMCE WYSIWYG editor
gem 'tinymce-rails'

# Use the database-backed adapters for Rails.cache, Active Job, and Action Cable
gem "solid_cache"
gem "solid_queue"
gem "solid_cable"

# Reduces boot times through caching; required in config/boot.rb
gem "bootsnap", require: false

# Deploy this application anywhere as a Docker container [https://kamal-deploy.org]
gem "kamal", require: false

# Add HTTP asset caching/compression and X-Sendfile acceleration to Puma [https://github.com/basecamp/thruster/]
gem "thruster", require: false

# Use Active Storage variants [https://guides.rubyonrails.org/active_storage_overview.html#transforming-images]
# gem "image_processing", "~> 1.2"

group :development, :test do
  # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
  gem "debug", platforms: %i[ mri ], require: "debug/prelude"

  # Static analysis for security vulnerabilities [https://brakemanscanner.org/]
  gem "brakeman", require: false

  # Omakase Ruby styling [https://github.com/rails/rubocop-rails-omakase/]
  gem "rubocop-rails-omakase", require: false

  # Load environment variables from .env
  gem "dotenv-rails"
end

group :development do
  # Use console on exceptions pages [https://github.com/rails/web-console]
  gem "web-console"
  gem "letter_opener"
end

group :test do
  # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
  gem "capybara"
  gem "selenium-webdriver"
end

gem "devise", "~> 4.9"
gem "kaminari"

gem "omniauth"
gem "omniauth-github"
gem "omniauth-linkedin-oauth2"

gem "activeadmin", "4.0.0.beta15"

gem "cssbundling-rails", "~> 1.4"

This app has already package.json file and I don't remember how I set it up :D . Any pointers?

Answered by setoelkahfi

Dec 27, 2025

This is what works for me:

Gemfile

source "https://rubygems.org"

gem "devise"

# Solana wallet generation
gem "ed25519"
gem "base58"

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
gem "rails", "~> 8.1"
# The modern asset pipeline for Rails [https://github.com/rails/propshaft]
gem "propshaft"
# Use postgresql as the database for Active Record
gem "pg", "~> 1.1"
# Use the Puma web server [https://github.com/puma/puma]
gem "puma", ">= 5.0"
# Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
gem "importmap-rails"
# Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
gem "turbo-rails"
# Hotwire's modest JavaScript fra…

View full answer

tagliala · 2025-12-14T17:12:52Z

tagliala
Dec 14, 2025
Maintainer

Hello, in the latest beta we switched to Tailwind CSS v4

gem "tailwindcss-rails", "~> 3.3.1"

This does not look correct

Please double check the upgrading guide, and please also compare your application with https://github.com/activeadmin/demo.activeadmin.info, it is a 8.1 Rails app running on the latest beta activeadmin which is proven to be working

2 replies

DanyloNovikov Dec 26, 2025

gem "activeadmin", "4.0.0.beta15", tailwind v4 was added in beta 19 and on the first screen you can see that there is a problem with loading Tailwind in general. I have the same issue with Tailwind and I installed v4.

tagliala Dec 26, 2025
Maintainer

When Tailwind was updated from v3 to v4, it introduced compatibility issues with a default Active Admin installation. Developers needed to explicitly set Tailwind to v3 for older versions.

For reference, see #8538 as well as commit 643fff6.

Note: The activeadmin/demo.activeadmin.info repository features working demo applications for both Tailwind v3 and v4.

Latest v3 demo: ecec69a

Please double check applications having issues against the demo application to understand what is going wrong with assets

setoelkahfi · 2025-12-27T08:45:43Z

setoelkahfi
Dec 27, 2025
Author

This is what works for me:

Gemfile

source "https://rubygems.org"

gem "devise"

# Solana wallet generation
gem "ed25519"
gem "base58"

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main"
gem "rails", "~> 8.1"
# The modern asset pipeline for Rails [https://github.com/rails/propshaft]
gem "propshaft"
# Use postgresql as the database for Active Record
gem "pg", "~> 1.1"
# Use the Puma web server [https://github.com/puma/puma]
gem "puma", ">= 5.0"
# Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
gem "importmap-rails"
# Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev]
gem "turbo-rails"
# Hotwire's modest JavaScript framework [https://stimulus.hotwired.dev]
gem "stimulus-rails"
# Use Tailwind CSS [https://github.com/rails/tailwindcss-rails]
gem "tailwindcss-rails", "~> 3.3.1"
# Build JSON APIs with ease [https://github.com/rails/jbuilder]
gem "jbuilder"

# Use Active Model has_secure_password [https://guides.rubyonrails.org/active_model_basics.html#securepassword]
# gem "bcrypt", "~> 3.1.7"

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem "tzinfo-data", platforms: %i[ windows jruby ]

# Use the database-backed adapters for Rails.cache, Active Job, and Action Cable
gem "solid_cache"
gem "solid_queue"
gem "solid_cable"

# Reduces boot times through caching; required in config/boot.rb
gem "bootsnap", require: false

# Deploy this application anywhere as a Docker container [https://kamal-deploy.org]
gem "kamal", require: false

# Add HTTP asset caching/compression and X-Sendfile acceleration to Puma [https://github.com/basecamp/thruster/]
gem "thruster", require: false

# Use Active Storage variants [https://guides.rubyonrails.org/active_storage_overview.html#transforming-images]
# gem "image_processing", "~> 1.2"

gem "activeadmin", "4.0.0.beta19"

group :development, :test do
  # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem
  gem "debug", platforms: %i[ mri windows ], require: "debug/prelude"

  # Static analysis for security vulnerabilities [https://brakemanscanner.org/]
  gem "brakeman", require: false

  # Omakase Ruby styling [https://github.com/rails/rubocop-rails-omakase/]
  gem "rubocop-rails-omakase", require: false
end

group :development do
  # Use console on exceptions pages [https://github.com/rails/web-console]
  gem "web-console"
  gem "letter_opener"
end

group :test do
  # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
  gem "capybara"
  gem "selenium-webdriver"
end

gem "cssbundling-rails", "= 1.4.1"

package.json:

{
  "name": "app",
  "private": "true",
  "packageManager": "[email protected]",
  "engines": {
    "node": ">=18.0.0",
    "pnpm": ">=10.0.0"
  },
  "scripts": {
    "preinstall": "npx only-allow pnpm",
    "build:css": "tailwindcss -i ./app/assets/stylesheets/application.tailwind.css -o ./app/assets/builds/application.css --minify -c tailwind.config.js && tailwindcss -i ./app/assets/stylesheets/active_admin.css -o ./app/assets/builds/active_admin.css --minify -c tailwind-active_admin.config.js"
  },
  "dependencies": {
    "@activeadmin/activeadmin": "4.0.0-beta19"
  },
  "devDependencies": {
    "only-allow": "^1.2.2",
    "tailwindcss": "^3.3.1"
  }
}

tailwind.config.js:

const defaultTheme = require('tailwindcss/defaultTheme')

module.exports = {
  content: [
    './public/*.html',
    './app/helpers/**/*.rb',
    './app/javascript/**/*.js',
    './app/views/**/*.{erb,haml,html,slim}'
  ],
  theme: {
    extend: {
      fontFamily: {
        sans: ['Inter var', ...defaultTheme.fontFamily.sans],
      },
    },
  },
  plugins: [
    // require('@tailwindcss/forms'),
    // require('@tailwindcss/typography'),
    // require('@tailwindcss/container-queries'),
  ]
}

tailwind-active_admin.config.js:

import { execSync } from "child_process";
import activeAdminPlugin from "@activeadmin/activeadmin/plugin";
import plugin from "tailwindcss/plugin";

const activeAdminPath = execSync("bundle show activeadmin", {
  encoding: "utf-8",
}).trim();

export default {
  content: [
    `${activeAdminPath}/vendor/javascript/flowbite.js`,
    `${activeAdminPath}/plugin.js`,
    `${activeAdminPath}/app/views/**/*.{arb,erb,html,rb}`,
    "./app/admin/**/*.{arb,erb,html,rb}",
    "./app/views/active_admin/**/*.{arb,erb,html,rb}",
    "./app/views/admin/**/*.{arb,erb,html,rb}",
    "./app/views/layouts/active_admin*.{erb,html}",
    "./app/javascript/**/*.js",
  ],
  darkMode: "selector",
  theme: {
    extend: {
      boxShadow: {
        xs: "0 0 0 1px rgba(0, 0, 0, 0.05)",
      },
    },
  },
  plugins: [
    activeAdminPlugin,
    plugin(function ({ addUtilities }) {
      addUtilities({
        ".scheme-dark": {
          "color-scheme": "dark",
        },
        ".scheme-light": {
          "color-scheme": "light",
        },
        ".outline-hidden": {
          outline: "2px solid transparent",
          "outline-offset": "2px",
        },
      });
    }),
  ],
};

2 replies

tagliala Dec 27, 2025
Maintainer

gem "tailwindcss-rails", "~> 3.3.1"

Even if this works, it does not sound to me.

Version 4.0.0.beta19 requires Tailwind CSS v4, but the configuration above is still pointing to Tailwind v3.

The reason might be that Tailwind isn’t being used directly by ActiveAdmin, which instead relies on cssbundling.

There are many ways to set this up, and ActiveAdmin may recommend one method, but there are plenty of alternative approaches that are equally valid. So feel free to use whatever works for your configuration. However, it is worth to point out this inconsistency

setoelkahfi Dec 27, 2025
Author

I'll investigate this further when I have the resource.

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