composer install --ignore-platform-req=php: skip one PHP or extension check

Composer checks platform requirements before installing: the PHP version (php), extensions (ext-intl, ext-gd) and system libraries (lib-*) that packages declare. When the machine running Composer does not satisfy them, the install stops with "Your requirements could not be resolved to an installable set of packages" or "Your lock file does not contain a compatible set of packages". --ignore-platform-req=ext-intl skips one of those checks; --ignore-platform-reqs (plural) skips all of them.

Common forms

composer install --ignore-platform-req=ext-intl        # one extension
composer install --ignore-platform-req=ext-*           # every extension (wildcard)
composer install --ignore-platform-req=php+            # only the upper bound of php
composer install --ignore-platform-reqs                # everything (last resort)
COMPOSER_IGNORE_PLATFORM_REQ=ext-intl composer install # environment variable form

Options compared

Better: declare the target platform

{
  "config": {
    "platform": {
      "php": "8.3.0",
      "ext-intl": "1.0"
    }
  }
}

With config.platform, Composer resolves packages for PHP 8.3 with intl on every machine, so the lock file fits production even when developers run another PHP version. Nothing is ignored; Composer simply knows what to target.

Pitfalls

• Ignoring a requirement does not make the code work. A package that needs ext-intl fails at runtime, typically with a missing class or function error, if the extension is really missing.
• Since Composer 2, vendor/composer/platform_check.php checks PHP and extensions at runtime and stops with Composer detected issues in your platform when they are missing, even if you installed with the flag.
• Missing zip or unzip is not a platform requirement but a Composer download problem: see The zip extension and unzip/7z commands are both missing.
• Resolution errors with other causes (conflicting versions) are explained in Your requirements could not be resolved.

FAQ