PHP 5.4 & Laravel Class 'Memcached' not found

# PHP 5.4 & Laravel Class 'Memcached' not found: Debugging a Common Caching Headache I realize there are about ten questions out there regarding caching setups, but none fit me completely. I’ve spent considerable time chasing this specific error: **`Fatal error: Class 'Memcached' not found`** within a Laravel application environment, even after seemingly successful installation of the Memcached PHP extension. This post will walk you through the likely causes and provide the definitive steps to resolve this frustrating disconnect between system configuration and application runtime. ## The Setup: What We Know So Far The user has followed the standard procedure for integrating Memcached with a PHP/Laravel stack: 1. Installed the `memcache` service (the actual server). 2. Installed the PHP module (`php-memcached`). 3. Updated Laravel configuration to point to the new cache driver. 4. Restarted the web server. The diagnostic output provided, including the `php info` results and the Memcached tool statistics, confirms that the underlying system components *seem* correctly installed and operational on the command line. The key discrepancy is happening when the application attempts to load the specific class (`Memcached`) within the Laravel framework context, specifically in `vendor/laravel/framework/src/Illuminate/Cache/MemcachedConnector.php`. ## The Root Cause: Extension Loading vs. Autoloading When you see a "Class not found" error in a modern PHP framework like Laravel, it rarely means the C extension itself is missing (which would typically cause a fatal error during startup). Instead, it usually points to an issue with how the autoloader or the environment loading the class definition is configured. In this specific scenario, the problem often lies in one of two areas: 1. **CLI vs. FPM Context