I will list here different problems and their resolutions when we are trying to deploy sandbox solutions. That might help me quickly resolve these in future.

Problem 1: Error occurred in deployment step ‘Retract Solution’: Cannot start service SPUserCodeV4

I was working on a project which involved creating a simple Webpart and must be tested in sandbox environment, I tried to deploy it after some initial working, I got that message on deployment.

Where did that service is, I looked around and found that I need to start that service in Central Administration, as outlined below.

1. Open Central Administration
2. Click on “System Settings”
3. Then click on “Manage services on this server”
4. A list of services will be displayed, some of them will be stopped
5. Look for “Microsoft SharePoint Foundation Sandboxed Code Service”
6. Click on “start” on the last column, your services will be started shortly.

Now go back to your solution and try re-deploying.