Enabling Session State: SharePoint 2010

To enable session state in SharePoint 2010 use these steps:

1- Execute this command: Enable-SPSessionStateService -DefaultProvision

(the above command can be executed with other switches. Check this link for more details)

2- Open web.config file of desired web application and search for "<pages"

Set enableSessionState="true"

3- Add this httpmodule in web.config

<httpmodules>

<add name="Session" type="System.Web.SessionState.SessionStateModule " />

</httpModules>

4- Search "remove name="Session" if found then comment this line in web.config