Unable to make the session state request to the session state server.

Problem:

This is an expansion of a post from Dec 15.

Solution:

These steps need to be checked to ensure that the state service is running
1.) Ensure HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\AllowRemoteConnection to 1
2.)Ensure that ASP.Net service is set to start automatically.
3.)Ensure that ASP.Net service is running.
4.)If you reset the registry key then restart the

ASP.net state service after you change the parameter.

5.)Check the web.config for the website locate the following attribute

<sessionState mode="StateServer" stateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1;Trusted_Connection=yes" cookieless="false" timeout="30" />

6.)Ensure that the port specified in the stateConnectionString, default is 42424 matches the port set in the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\Port 42424
7.)Ensure that Firewall is not blocking port 42424.

Source:

1.) http://fetchmytip.blogspot.com/2015/12/iis-85-unable-to-make-session-state.html
2.)http://forums.asp.net/t/1222433.aspx?Unable+to+make+the+session+state+request+to+the+session+state+server+

IIS 8.5 - Unable to make the session state request to the session state server.

Problem: 

Got this jewel of an error message after coming in from a great weekend

Solution:

As the error message mentions,  I checked the asp.net service

And yes, the service was disabled and set to manual.  I set it to active and automatic.  But this issue was still there.

Next I checked the registry setting.

Set the value to 1 and rebooted.

Problem Solved!