Server Error in '/' Application


Key duplication when adding: sessionState

Description: HTTP 500. Error processing request.

Stack Trace:

System.ArgumentException: Key duplication when adding: sessionState
  at System.Collections.Hashtable.PutImpl (System.Object key, System.Object value, Boolean overwrite) [0x00000] in <filename unknown>:0 
  at System.Collections.Hashtable.Add (System.Object key, System.Object value) [0x00000] in <filename unknown>:0 
  at System.Collections.Specialized.NameObjectCollectionBase.BaseAdd (System.String name, System.Object value) [0x00000] in <filename unknown>:0 
  at System.Collections.Specialized.NameObjectCollectionBase.BaseSet (System.String name, System.Object value) [0x00000] in <filename unknown>:0 
  at System.Configuration.ConfigurationSectionCollection.get_Item (System.String name) [0x00000] in <filename unknown>:0 
  at System.Configuration.Configuration.GetSection (System.String path) [0x00000] in <filename unknown>:0 
  at System.Web.Configuration.WebConfigurationManager.GetSection (System.String sectionName, System.String path, System.Web.HttpContext context) [0x00000] in <filename unknown>:0 
  at System.Web.Configuration.WebConfigurationManager.GetSection (System.String sectionName) [0x00000] in <filename unknown>:0 
  at System.Web.SessionState.SessionStateModule.Init (System.Web.HttpApplication app) [0x00000] in <filename unknown>:0 
  at System.Web.Configuration.HttpModulesSection.LoadModules (System.Web.HttpApplication app) [0x00000] in <filename unknown>:0 
  at System.Web.HttpApplication.InitOnce (Boolean full_init) [0x00000] in <filename unknown>:0 

Version information: Mono Runtime Version: 2.10.8 (tarball So kvÄ› 11 18:15:08 CEST 2013); ASP.NET Version: 4.0.30319.1