Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires whikloj/bagittools ^3.0 -> satisfiable by whikloj/bagittools[3.0.0, 3.0.1, 3.0.2]. - whikloj/bagittools[3.0.0, ..., 3.0.2] require ext-intl * -> it is missing from your system. Install or enable PHP's intl extension. To enable extensions, verify that they are enabled in your .ini files: - /usr/local/etc/php/conf.d/docker-php-ext-gd.ini - /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini - /usr/local/etc/php/conf.d/docker-php-ext-zip.ini You can also run `php --ini` in a terminal to see which files are used by PHP in CLI mode. Alternatively, you can run Composer with `--ignore-platform-req=ext-intl` to temporarily ignore these required extensions.