When publishing a SharePoint hosted application to a development site on Office 365 , running SharePoint 2013, you may receive the following error:
“Error occurred in deployment step ‘Install App for SharePoint’: Sideloading of apps is not enabled on this site.
Solution: You need to enable the Sideloading feature on the site.
1. Download and install the SharePoint Online Management Shell for PowerShell
2. Download the script Sideload.ps1 and execute it within the SharePoint Online Management Shell.
Note: This is not recommended for a production site. Deploy applications using the App Catalog on a production site.