Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires nikic/fast-route ~1.0 -> satisfiable by nikic/fast-route[v1.0.0, ..., v1.3.0]. - nikic/fast-route[v1.0.0, ..., v1.3.0] require php >=5.4.0 -> your php version (5.3.29) does not satisfy that requirement. Problem 2 - Root composer.json requires phroute/phroute ~2.0 -> satisfiable by phroute/phroute[v2.0.0, v2.1.0, v2.2.0]. - phroute/phroute[v2.0.0, ..., v2.2.0] require php >=5.4.0 -> your php version (5.3.29) does not satisfy that requirement. Problem 3 - Root composer.json requires zendframework/zend-diactoros ~2.0 -> satisfiable by zendframework/zend-diactoros[2.0.0, ..., 2.2.1]. - zendframework/zend-diactoros[2.0.0, ..., 2.2.1] require php ^7.1 -> your php version (5.3.29) does not satisfy that requirement. Problem 4 - Root composer.json requires zendframework/zend-stratigility ~3.0 -> satisfiable by zendframework/zend-stratigility[3.0.0, ..., 3.2.0]. - zendframework/zend-stratigility[3.0.0, ..., 3.2.0] require php ^7.1 -> your php version (5.3.29) does not satisfy that requirement. Problem 5 - filp/whoops[2.0.0, ..., 2.1.3] require php >=5.5.9 -> your php version (5.3.29) does not satisfy that requirement. - filp/whoops[2.1.4, ..., 2.7.3] require php ^5.5.9 || ^7.0 -> your php version (5.3.29) does not satisfy that requirement. - filp/whoops[2.8.0, ..., 2.15.4] require php ^5.5.9 || ^7.0 || ^8.0 -> your php version (5.3.29) does not satisfy that requirement. - Root composer.json requires filp/whoops ~2.0 -> satisfiable by filp/whoops[2.0.0, ..., 2.15.4].