Fix Composer Detected Issues in Your Platform: PHP Version Required (4 Solutions)

When deploying PHP or Laravel applications, few errors halt a deployment faster than this fatal runtime blocker:

Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 8.2.0". You are running 8.1.18.
PHP Fatal error: Composer detected issues in your platform in /var/www/html/vendor/composer/platform_check.php on line 28

This error is generated by Composer's built-in platform_check.php file, which validates that your active PHP runtime matches the constraints defined in composer.lock.

Here are the 4 production-grade methods to resolve it.

Why This Error Happens

Composer packages declare minimum PHP versions and required extensions in composer.json. During composer install, Composer generates a verification file at vendor/composer/platform_check.php.

If you run composer install locally with PHP 8.2, but your production server or Docker container runs PHP 8.1, the platform check aborts execution before your application even boots.

Solution 1: Lock Platform Requirements in composer.json (Recommended for Teams)

If developers use different local PHP versions than your production server, tell Composer explicitly which PHP version to target regardless of local CLI versions:

Add the platform key inside your composer.json config block:

{
    "config": {
        "platform": {
            "php": "8.2.20"
        }
    }
}

Regenerate the lock file:

composer update --lock

Now, Composer will always resolve packages compatible with PHP 8.2.20, preventing discrepancies between staging and production.

Solution 2: Switch Your CLI PHP Version

If your server has multiple PHP versions installed, your web server (e.g. PHP-FPM) might be running PHP 8.2 while your CLI terminal defaults to PHP 8.1.

Check CLI version:

php -v

On Ubuntu / Debian, switch the active CLI version using update-alternatives:

sudo update-alternatives --set php /usr/bin/php8.2
sudo update-alternatives --set phar /usr/bin/phar8.2

Verify again with php -v. Once the version matches, clear Composer autoload:

composer dump-autoload

Solution 3: Disable Platform Check During Deployment

If your server runtime is compatible but slightly different from your local environment, you can disable the platform check file generation entirely:

composer install --no-dev --optimize-autoloader --no-plugins --ignore-platform-req=php

Or configure it permanently in composer.json:

{
    "config": {
        "platform-check": false
    }
}

Warning: Only disable platform-check if you are certain that your code does not use language features or syntax introduced in newer PHP versions.

Solution 4: Rebuild Autoloader in Production

If you recently upgraded PHP on your server (e.g., from 7.4 to 8.2) and the old check still runs:

rm -rf vendor/composer/platform_check.php
composer dump-autoload --optimize