Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires yiisoft/db dev-refactor-test as dev-master -> satisfiable by yiisoft/db[dev-refactor-test]. - yiisoft/db dev-refactor-test requires psr/simple-cache-implementation * -> could not be found in any version, but the following packages provide it: - laravel/framework The Laravel Framework. - symfony/cache Provides extended PSR-6, PSR-16 (and tags) implementations - illuminate/cache The Illuminate Cache package. - symfony/symfony The Symfony PHP framework - cakephp/cakephp The CakePHP framework - laminas/laminas-cache Caching implementation with a variety of storage options, as well as codified caching strategies for - cache/filesystem-adapter A PSR-6 cache implementation using filesystem. This implementation supports tags - phpfastcache/phpfastcache PHP Abstract Cache Class - Reduce your database call using cache system. Phpfastcache handles a lot - cache/simple-cache-bridge A PSR-6 bridge to PSR-16. This will make any PSR-6 cache compatible with SimpleCache. - matthiasmullie/scrapbook Scrapbook is a PHP cache library, with adapters for e.g. Memcached, Redis, Couchbase, APCu, SQL and - cache/array-adapter A PSR-6 cache implementation using a php array. This implementation supports tags - ibericode/vat PHP library for dealing with EU VAT - cache/apcu-adapter A PSR-6 cache implementation using apcu. This implementation supports tags - cache/redis-adapter A PSR-6 cache implementation using Redis (PhpRedis). This implementation supports tags - neos/cache Neos Cache Framework ... and 174 more. Consider requiring one of these to satisfy the psr/simple-cache-implementation requirement. Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details. - It's a private package and you forgot to add a custom repository to find it Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.