Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires hershel-theodore-layton/hhvm-four-shim ^1, found hershel-theodore-layton/hhvm-four-shim[dev-master, dev-backports, v0.4.0, v0.6.1] but it does not match the constraint. Problem 2 - Root composer.json requires hershel-theodore-layton/test-chain dev-master -> satisfiable by hershel-theodore-layton/test-chain[dev-master]. - hershel-theodore-layton/test-chain dev-master requires hershel-theodore-layton/hhvm-four-shim <1 -> found hershel-theodore-layton/hhvm-four-shim[v0.4.0, v0.6.1] but it conflicts with your root composer.json require (^1). Problem 3 - Root composer.json requires hershel-theodore-layton/expect dev-master -> satisfiable by hershel-theodore-layton/expect[dev-master]. - hershel-theodore-layton/expect dev-master requires hershel-theodore-layton/hhvm-four-shim <1 -> found hershel-theodore-layton/hhvm-four-shim[v0.4.0, v0.6.1] but it conflicts with your root composer.json require (^1).