Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires simplesamlphp/simplesamlphp ^2.1 -> satisfiable by simplesamlphp/simplesamlphp[2.1.0, ..., v2.4.4]. - simplesamlphp/simplesamlphp[2.1.0, ..., v2.4.4] require ext-session * -> it is missing from your system. Install or enable PHP's session extension. To enable extensions, verify that they are enabled in your .ini files: - /etc/php84/php.ini - /etc/php84/conf.d/00_ctype.ini - /etc/php84/conf.d/00_curl.ini - /etc/php84/conf.d/00_dom.ini - /etc/php84/conf.d/00_iconv.ini - /etc/php84/conf.d/00_intl.ini - /etc/php84/conf.d/00_mbstring.ini - /etc/php84/conf.d/00_openssl.ini - /etc/php84/conf.d/00_simplexml.ini - /etc/php84/conf.d/00_tokenizer.ini - /etc/php84/conf.d/00_xmlwriter.ini - /etc/php84/conf.d/01_phar.ini - /etc/php84/conf.d/10_igbinary.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-session` to temporarily ignore these required extensions.