Security Exception (Index Site Content)

While trying to access the "Index Site Content" - /EPiServer/EPiServer.Search.Cms/IndexContent.aspx (in cms 11)
Im met with a Security Exception :

Description: The application attempted to perform an operation not allowed by the security policy.  To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file. 

Exception Details: System.Security.SecurityException: Request for principal permission failed.

[SecurityException: Request for principal permission failed.]
   System.Security.Permissions.PrincipalPermission.ThrowSecurityException() +257
   System.Security.Permissions.PrincipalPermission.Demand() +496
   System.Security.PermissionSet.DemandNonCAS() +146
   EPiServer.UI.Admin.IndexContent..ctor() +35
   ASP.episerver_episerver_search_cms_indexcontent_aspx..ctor() +58
   __ASP.FastObjectFactory_app_web_gmuadrnl.Create_ASP_episerver_episerver_search_cms_indexcontent_aspx() +63
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) +132
   System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +44
   System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +377
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +134

The problem is that it works fine on my local machine, and this only happens on the production enviroment. I cant seem to figure out whats wrong. Accessing other tools such as export, import
Manage Content, Change log etc all works. I noticed this issue when it seemed like the search had stopped working after the update from cms 10 -> 11.