I have travis-ci integrated with my GitHub account (https://github.com/pradeep0601/Angular5-Router-App).
When I updated @angular/cli versio
Check your folder structure where you are executing the command, you should run the command 'ng serve' where there should be a angular.json file in the structure.
angular.json file will be generated by default when we run the command
npm install -g '@angular/cli' ng new Project_name then cd project_folder then, run ng serve. it worked for me