Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires ergebnis/php-cs-fixer-config ^6.49.0 -> satisfiable by ergebnis/php-cs-fixer-config[6.49.0]. - ergebnis/php-cs-fixer-config 6.49.0 requires friendsofphp/php-cs-fixer ~3.82.0 -> satisfiable by friendsofphp/php-cs-fixer[v3.82.0, v3.82.1, v3.82.2]. - friendsofphp/php-cs-fixer[v3.82.0, ..., v3.83.0] require symfony/polyfill-mbstring ^1.32 -> satisfiable by symfony/polyfill-mbstring[v1.32.0, 1.x-dev]. - symfony/polyfill-mbstring[v1.32.0, ..., 1.x-dev] require ext-iconv * -> it is missing from your system. Install or enable PHP's iconv extension. Alternatively you can require one of these packages that provide the extension (or parts of it): Keep in mind that the suggestions are automated and may not be valid or safe to use - symfony/polyfill-iconv Symfony polyfill for the Iconv extension To enable extensions, verify that they are enabled in your .ini files: - /etc/php/7.4/cli/php.ini - /etc/php/7.4/cli/conf.d/15-xml.ini - /etc/php/7.4/cli/conf.d/20-ctype.ini - /etc/php/7.4/cli/conf.d/20-curl.ini - /etc/php/7.4/cli/conf.d/20-dom.ini - /etc/php/7.4/cli/conf.d/20-json.ini - /etc/php/7.4/cli/conf.d/20-mbstring.ini - /etc/php/7.4/cli/conf.d/20-phar.ini - /etc/php/7.4/cli/conf.d/20-simplexml.ini - /etc/php/7.4/cli/conf.d/20-tokenizer.ini - /etc/php/7.4/cli/conf.d/20-xmlwriter.ini - /etc/php/7.4/cli/conf.d/99-pecl.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-iconv` to temporarily ignore these required extensions. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.