Fix require(vendor/autoload.php): Failed to Open Stream Error in PHP & Laravel – Step-by-Step Beginner Guide

“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Outdated autoload files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