Request for the permission of type 'System.Net.WebPermission error only for sandboxed solutions

Question

I have created a farm solutions to access external webservice an created a webpart. After deployed the solution it works fine. Then requirement has been changed. So I changed the application to sandboxed, it endsup with error. I debug the code and it returns an exception.

Request for the permission of type 'System.Net.WebPermission, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. This is my code where exception was thrown.

 WebRequest req = WebRequest.Create(@"https://URL");

In my sharepoint site I find the below error in webpart.

Web Part Error: Unhandled exception was thrown by the sandboxed code wrapper's Execute method in the partial trust app domain: An unexpected error has occurred.

Answer 1

Sandbox is an isolated environment that do not allow you to call anything outside that environment. A call through a web url away is a call outside the sandbox, requiring System.Net.WebPermissions. This is prohibited by the Code Access Security policies defined for the Sandbox.

You have 2 options here.

1. Use JavaScript Client Object Model
2. Build a Sandbox Proxy solution