Error : ‘Install app for SharePoint’: Sideloading of apps is not enabled on this site.
This error occurred when you try to deploy app, reason for this error is not activated the developer feature on the SharePoint site where you want to deploy and test your application. The solution is to run SharePoint power shell and run following command: Enable-SPFeature e374875e-06b6-11e0-b0fa-57f5dfd72085 -url http://webapplication