The requested resource / was not found on this server. existing project yii serve Not found home page in local ubuntu setup

It’s an issue with the route. Check this documentation: Handling Requests: Routing and URL Creation | The Definitive Guide to Yii 2.0 | Yii PHP Framework

The default route is site/index. Typically the yii2 application is generated with a controller called SiteController.php and has an actionIndex to satisfy the default route. Make sure all of those are in place.