Best Headless CMS Wordpres: How To Install Sage Theme – 100% Working

wordpress

If you’ve ever tried setting up Sage 10 with Acorn and Vite and felt like you were losing your mind, you’re not alone.

I recently went through the whole mess too — broken themes, missing PHP extensions, Vite build errors, and Acorn refusing to behave. So here’s the real-world setup guide I wish someone handed me at the start.

This article is based on real-world debugging, not just the happy-path setup instructions. Here’s what worked for me — and what I wish I knew at the start.

Step 1: Fix your PHP setup first

The #1 issue that’ll break your install is a missing PHP extension. You’ll usually get errors like: league/flysystem-local requires ext-fileinfo

That’s because your php.ini doesn’t have fileinfo enabled — and yes, it needs to be the actual php.ini file, not php.ini-development or php.ini-production.

Configurate the .php.ini

Run php –ini in your terminal or you can usually find this on C:\Program Files\PHP\php.ini . Please make sure that you are updating the right .php.ini because they have both production and development. Then open that file and make sure this line is uncommented then restart your terminal or web server

php 
extension=php_fileinfo.dll

Step 2. Install Acorn 5.0.3 before Sage (Recommend if you run other than Sage)

Do this before installing Sage, or things will break later. Acorn is the engine behind Sage’s Laravel-style functionality (like Blade and the container).

php 


composer require roots/acorn:^5.0.3 –with-all-dependencies

This can be run in your main Bedrock app, or even just to verify your system dependencies and PHP are ready. It’s useful for:

  • Checking for any global conflicts (like fileinfo, illuminate/*, etc.)
  • Testing if your PHP setup supports Acorn
  • Think of this like testing your car engine before going on a road trip.

Step 3: Create a new Sage theme (and install Acorn inside it too)

php 


composer create-project roots/sage your-theme-name

cd your-theme-name
php 


composer require roots/acorn:^5.0.3 –with-all-dependencies

Step 4: Run Vite build (this will save you from 500 errors)

Now your theme’s code is set up, but the browser doesn’t know what to do with the JS and CSS until you compile it.

Run the following command inside the Sage theme

php 


npm install

npm run build

This will generate your assets in:

php 
/public/build/manifest.json