I have created a new visual web part in SharePoint 2013 as a sandboxed solution. I can see the web part in the Webpart gallery. But when I Click F5 in my VS.net, the web part is working fine. As soon as I stop debugging, the web part is not working. I can see the following error.
The request could not be completed because the specified solution was not found.. - Validating solution failed
How do I fix this error?