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!