Composer 2.0 Release Issues / Support

[Seldaek]

🎉🥳 Composer 2 was just released! 🥳🎉

... but your stuff broke? 😞

If you wish to downgrade to Composer 1.x for the time being

• Run composer self-update --1 if you are using a composer.phar.
• Pass --1 to composer-setup.php or installer or whatever the installer is called if you have automated the installation process.
• If you have hardcoded a URL to https://getcomposer.org/composer-stable.phar for example, you can change that to https://getcomposer.org/composer-1.phar to get v1.

However, Composer 1.x will not be maintained for very long, so if you do this please remember it and aim to upgrade to Composer 2.x in a timely manner.

Here is a collection of top issues/workarounds:

• Hosting provider not supporting Composer 2? See How to prefer Composer Plugin versions that work both with Composer 1 and 2 #9474 (comment) for workarounds.
• Using Symfony and symfony/flex? Make sure you composer update symfony/flex to get it to 1.12.2+ for full Composer 2 compatibility
• Using Laravel 6 or 7, you get Undefined index: name? See Undefined index: name errors using Composer 2.01 for updating Laravel 6 #9340 (comment) for a solution.
• Using Drupal? See the upgrade guide.
• Using Magento? Upgrade to 2.4.2 (or 2.3.7 once it is out) or if you can not do that you can try these non-official instructions to upgrade.
• Using hirak/prestissimo? Remove it as it is not needed anymore in Composer 2, and will prevent you from updating or add warnings to every command you run.