Fatal error: Uncaught Error: Interface "Psr\Http\Message\ResponseInterface" not found in /Users/ppss/Sites/PPSS/api/vendor/slim/http/src/Interfaces/ResponseInterface.php:15 Stack trace: #0 {main} thrown in /Users/ppss/Sites/PPSS/api/vendor/slim/http/src/Interfaces/ResponseInterface.php on line 15