Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit ^11 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.1.3]. - phpunit/phpunit[11.0.0, ..., 11.1.3] require php >=8.2 -> your php version (8.1.28) does not satisfy that requirement. Problem 2 - timacdonald/callable-fake v1.8.0 requires phpunit/phpunit ^10.0 || ^11.0 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.1.3]. - timacdonald/callable-fake v1.7.0 requires phpunit/phpunit ^9.0 || ^10.0 || ^11.0 -> satisfiable by phpunit/phpunit[11.0.0, ..., 11.1.3]. - timacdonald/callable-fake[v1.0.0, ..., v1.2.0] require php ^7.1 -> your php version (8.1.28) does not satisfy that requirement. - timacdonald/callable-fake[v1.3.0, ..., v1.5.0] require phpunit/phpunit ^6.0 || ^7.0 || ^8.0 || ^9.0 -> found phpunit/phpunit[6.0.0, ..., 6.5.14, 7.0.0, ..., 7.5.20, 8.0.0, ..., 8.5.38, 9.0.0, ..., 9.6.19] but it conflicts with your root composer.json require (^11). - timacdonald/callable-fake v1.6.0 requires phpunit/phpunit ^9.0 || ^10.0 -> found phpunit/phpunit[9.0.0, ..., 9.6.19, 10.0.0, ..., 10.5.20] but it conflicts with your root composer.json require (^11). - phpunit/phpunit[11.0.0, ..., 11.1.3] require php >=8.2 -> your php version (8.1.28) does not satisfy that requirement. - Root composer.json requires timacdonald/callable-fake ^1.0 -> satisfiable by timacdonald/callable-fake[v1.0.0, ..., v1.8.0].