Make sure you have updated your Composer to the latest version, read https://discourse.hkvstore.com/t/interface-psr-http-message-requestfactoryinterface-not-found/3419/1
Make sure you have updated your Composer to the latest version, read https://discourse.hkvstore.com/t/interface-psr-http-message-requestfactoryinterface-not-found/3419/1