Composer detected issues in your platform: Your Composer dependencies require
Since Composer 2, vendor/composer/platform_check.php runs on every request and stops the app if the PHP running it is older than the locked packages need. The trap is two PHP binaries: composer install ran under CLI PHP 8.3 (in CI or on your laptop) while the web server runs PHP-FPM 8.1, so php -v looks fine and the site still fails. Turning the check off only hides it. Align the versions, or set config.platform.php so the lock file is resolved for the PHP that actually serves traffic.
Quick fix
Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.
# Which PHP does the CLI use, and which versions are installed?
php -v
ls /etc/php/ 2>/dev/null
# The web server may differ: check "PHP Version" on a temporary phpinfo() page
# What do the locked packages demand?
composer check-platform-reqs --lock
# Resolve dependencies for the PHP version production really runs
composer config platform.php 8.1.27
composer update
# Or run composer with the same binary production uses
/usr/bin/php8.1 "$(command -v composer)" install --no-dev
# Avoid this: it silences the check and the app breaks later instead
# composer config platform-check falseHow to diagnose PHP errors
PHP errors are dominated by per-request resource limits (memory_limit, max_execution_time) and by autoloading. Class-not-found errors are almost never missing code. They are a namespace that does not match the PSR-4 mapping, or a stale Composer autoload map. Laravel adds a caching layer that produces genuinely confusing errors when configuration is cached with the wrong environment.
If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.
- Read the real limits from the running process, not from a config file:
php -i | grep -E 'memory_limit|max_execution_time'. CLI and FPM have separate configurations. - Regenerate the autoload map with
composer dump-autoload -obefore investigating a class-not-found error any further. - For Laravel, clear cached config and routes with
php artisan optimize:clear. A config cache built in the wrong environment causes errors that survive every code change. - Enable full error display in development (
display_errors=On,error_reporting=E_ALL). The default production settings hide the cause. - For PDO connection refusals, test the same credentials with the database's own CLI client to separate PHP configuration from database access.
Tools worth reaching for
php -icomposer dump-autoload -ophp artisan optimize:clearXdebugtail -f storage/logs/laravel.log
Authoritative references
Primary documentation for this error, worth reading before applying any fix in production.
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Something missing or wrong?
This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.