“Learn how to fix the common PHP and Laravel error require(vendor/autoload.php): failed to open stream. Step-by-step solutions with composer install and composer dump-autoload explained for beginners and junior developers.” Content Structure / Headings: Introduction Explain the error in simple terms. Why it happens for beginners and junior developers. What Causes require(vendor/autoload.php) Error Missing vendor folder Cloning project without running Composer Outdated autoload files Step 1: Install Composer Dependencies composer install Explain what it does. Step 2: Regenerate Autoload Files composer dump-autoload How it fixes class loading issues. Step 3: Laravel Specific Tips php artisan optimize:clear php artisan config:clear php artisan route:clear Additional Checks for Beginners Run commands from project root Check Composer version Check PHP version Conclusion & Best Practices Keep vendor in .gitignore Always run Composer commands after cloning a project Back