The method _getSourceByType($type, $source) in the class ConvertMappingTask has a little error: there are no brackets when propery getConfiguration are called. See code below, the error occurs on line marked with red: private function _getSourceByType($type, $source) { // If --from==database then the source is an instance of SchemaManager // for the current EntityMAnager if ($type == 'database') { $em = $this->getConfiguration->getAttribute('em'); return $em->getConnection()->getSchemaManager(); } else { return $source; } }