Composer の一般的なエラーとその解決策

vagrant@homestead:/usr/share/nginx/html/laravel-blog$ sudocomposerinstall Loadingcomposerrepositorieswithpackage information Installingdependencies (includingrequire-dev) fromlockfile Yourrequirementscouldnot beresolvedto aninstallablesetofpackages. Problem 1 - Installationrequestfor doctrine/instantiator 1.0.3 -> satisfiablebydoctrine/instantiator[1.0.3]. - doctrine/instantiator 1.0.3 requiresphp ~5.3 -> yourPHPversion (7.0.3) doesnot satisfythatrequirement. Problem 2 - doctrine/instantiator 1.0.3 requiresphp ~5.3 -> yourPHPversion (7.0.3) doesnot satisfythatrequirement. - phpunit/phpunit-mock-objects 2.3.0 requiresdoctrine/instantiator ~1.0,>=1.0.1 -> satisfiablebydoctrine/instantiator[1.0.3]. - Installationrequestfor phpunit/phpunit-mock-objects 2.3.0 -> satisfiablebyphpunit/phpunit-mock-objects[2.3.0].

composerinstall --ignore-platform-reqs

composerupdate --ignore-platform-reqs

Cannotcreatecachedirectory /home/vagrant/.composer/cache/repo/https---packagist.org/, or directoryis not writable. Proceedingwithoutcache Cannotcreatecachedirectory /home/vagrant/.composer/cache/files/, or directoryis not writable. Proceedingwithoutcache

sudo chmod -R 777 /home/vagrant/.composer/cache/files/