How to switch in different composer version in ubuntu To switch between different Composer versions on Ubuntu, particularly between major versions like Composer 1 and Composer 2, you can use the self-update command with specific flags. Switching between Composer 1 and Composer 2: To switch to Composer 1. composer self-update --1 To switch to Composer 2.  composer self-update --2 Other useful self-update commands: To update to the latest stable version (usually Composer 2): composer self-update To revert to the previous Composer version: composer self-update --rollback To preview a new Composer version before updating: composer self-update --preview Important Notes: If you encounter permission errors when running composer self-update , you might need to run it with sudo , like sudo composer self-update --2 . However, be cautious when using sudo with Composer, as it can sometimes lead to permission issues in your user's home directory. Ensure your PHP environment is compatible with the Composer version you are switching to. Different Composer versions might have different PHP version requirements. After switching versions, you can verify the current Composer version by running: composer --version